BCWINTERS  Can't believe how quickly Fluid has radically altered the way I use my Mac. No more juggling tabs and windows in Safari to keep an eye on Gmail or the bug tracker at work...now I have separate apps for each one. How about a mini-browser for Hulu that floats above my other windows...or a preview browser for website development that never gets its tabs mixed in with my personal browsing? You get the gist--Fluid makes it possible, not to mention dead simple. I don't think I could work without it anymore.  
(Version 0.9.6)

BCWINTERS  I needed to do some work on a Windows-only database, and decided to give VirtualBox a try before shelling out for Fusion. And boy am I glad I did.

This program has a surprisingly terrific level of polish and excellent (if somewhat techy) documentation.

While the UI isn't truly native it's very intuitive and quite nicely finished, and anyway you only touch the UI for a little while when setting up a new guest OS.

I had XP and my development tools installed in less time than it would have taken on a real PC (thanks to disk images instead of CDs!), and only needed to tweak one setting in the prefs to get access to my office's PPTP VPN--I think it was switching the "Attached To" setting to "Bridged" instead of "NAT," IIRC.

From there on out, it was smooth, speedy sailing. I love you, VirtualBox.  
(Version 2.2.4)

BCWINTERS  Saved my external firewire drive that had been incorrectly ejected (and had a damaged partition table as a result). DiskWarrior couldn't do it; Drive Genius couldn't do it; TechTool couldn't do it...yet tiny open source freeware TestDisk (along with companion command line utility pdisk) salvaged the partitions in a matter of maybe four minutes.

The documentation (like that of so many open source projects) is a bit arcane, and those of you who are not comfortable in the Terminal might be a little nervous about this app. But I found a walkthrough that made it dead simple.

This is a brilliant little utility that's going right into my recovery arsenal.  
(Version 6.10)

BCWINTERS  Still hoping to see an update to the Tiger version so as to incorporate the last three months of development. I've had to uninstall the plugin due to incompatibilities (which have been fixed in the Leopard version) and would really like to have it back again.  
(Version 1.4.1)

BCWINTERS  Love this. I keep vacillating between Firefox and Safari and this is tipping the scales back in Safari's favor. However, I do wish it worked with Tiger! There was a fork of the project that did (which is what I'm actually using), but it is a few versions behind and doesn't work as well as the Leopard-only version does. Hopefully the volunteers working on ClickToFlash will merge the forks sooner rather than later.  
(Version 1.4fc3)

BCWINTERS  The README that accompanies v3.0 says that source code is available on the app's SourceForge page, but the notes file on the web page says the code hasn't been released because it's too messy.

I'm grateful that the developer of this handy little app has started working on it again and I hope he finds time to do some "housecleaning" on the code--I would love to see if input from some other programmers could get 3.0 running on Tiger, for instance, and it would be great if the bug with accented characters in show names/descriptions could be fixed so those shows could be transferred.  
(Version 3.0)

BCWINTERS  Plays Windows Media files with no stuttering, delays or frame drops on my PowerBook, unlike recent versions of VLC or Flip4Mac! FLV playback is also much cleaner than in VLC, and with less CPU spiking.

For the moment, VLC will probably remain my "Swiss army knife" of video players but Movist is turning out to be a great supplemental player.

Some issues I have with Movist so far: the player controls are a bit large/intrusive when you want to have a floating video window while working on other things; there are no cropping settings (not that those work right in recent versions of VLC anyway); there's no way to disable on-screen display. It's also crashed once or twice on me when changing a lot of settings quickly while a video is playing (easy enough to avoid--in normal playback it's been crash free). Those are minor issues and I hope this program continues to be developed.  
(Version 0.51)

BCWINTERS  As someone who has VLC running almost constantly when I'm using my Mac, I've really been disappointed with the updates of the past year or so. The last version that I find really usable is 0.8.6c, but I keep trying newer versions in search of a handful of feature improvements (most notably because 0.8.6c can't fast forward or rewind FLV files).

0.9.4 is the first version in a year I'd even consider keeping--it handles FLV files properly, and it seems to have cleaned up many of the bugs of the more recent versions: it deals with full screen properly (the last few versions always crashed) and it handles my "second monitor" connection to my TV when I want it to.

But:

Video resizing is screwed up in this version (if you crop a video that's encoded with the wrong aspect information, you can't resize the window to eliminate the "bars") although at least the cropping is respected in full-screen mode;

There's a new, second controller stuck onto the bottom of the playback window, which can be disabled but only if you ALSO disable the resize control and the titlebar for some reason;

The new "basic" preferences window introduces mutually-exclusive settings that don't match with those in the "all" preferences window (why is there an "add controls to video window" pref in Basic, and a "window decorations" control in All? They don't seem to do the same thing);

Drag and drop onto the Controller no longer works; only the dock icon will accept drag and drop;

The Info window no longer displays file information like the dimension of the video in pixels, etc;

Sigh. Back to the drawing board, yet again. I'm really glad VLC is constantly under the eye of its developers and obviously the updates must be improving things for some users, but I wish some basic improvements would be made to get this back to being the lean-and-mean playback machine it used to be. I'm going back to 0.8.6c again.  
(Version 0.9.4)

BCWINTERS  I've been a long time hand-coder, using BBEdit and Transmit as two of my core tools. But facing a long slog of debugging PHP code on the server side seemed kind of headachey without a good live preview, so I thought I'd give Coda a try.

It is without a doubt a supremely polished piece of software--no crashes in 20 hours of (almost completely intuitive) use over the last two days. For those looking for a change from a multi-program workflow, or those stepping from Dreamweaver into more hand-coding, it's a great choice.

I can certainly think of a few feature improvements and tweaks I'd love to see: the Convert to ASCII tool isn't smart at all the way BBEdit's is; the Clips window is trendy but kind of gets in the way (and Clips could use better keyboard shortcut support); it would be great to limit text line length while still providing a nice wide web preview window; file listings can't be sorted.

But all in all, this is a terrific program that just helped me through a complicated project quite ably, even though I was using the demo (how awesome that it's totally not crippled). It might be hard to justify purchasing it since I already have a great FTP program and a great text editor, but I'm sure a few more upgrades and development cycles will make it irresistible  
(Version 1.1)

BCWINTERS  I'm pretty reliant on this little utility but it seems every time there's a system update it ceases to work for a while. I've never been able to figure out what gets it to kick back in again. It would be nice to see a quick maintenance update to address this.

Otherwise, it's a great timesaver that I use just about every day!  
(Version 2.1.1)

BCWINTERS  I just upgraded from 2.5.0.0 to 2.5.04 and it hasn't been the smoothest version change.

Clearly a lot of polish has gone into the interface, with new icons and lots of tidying done to the column widths (finally, I can fit all the columns I want to see on my PowerBook without 1/4" margins on the edge of each column!). However, the UI has become frighteningly unresponsive, taking upwards of 30 seconds to sort by a column and giving me 5 seconds of "rainbow beachball" every 5 seconds when I'm not doing anything other than watching the standard My Torrents window.

Having the My Torrents window open also now pegs my CPU up around 70% when previous versions never went much above 20 or 30. Closing the tab drops CPU usage down around 9-10%. There must be some screen drawing bug in this version or something.

If you've been holding off on an upgrade lately I recommend waiting another round or two until this gets sorted.  
(Version 2.5.04)

BCWINTERS  I launched TivoDecode Manager, entered my TiVo's IP address and media access key, and within 10 seconds I was backing up a recording of a news program I'd been saving since 2003! Excellent.

This app is still rough around the edges, though--I'd rather see the IPs and media access keys stored in the keychain; the progress bar sometimes stalls and times out (I just occasionally Get Info on the ripped file to see when it has stopped getting larger); there's no frames-per-second or other useful metric to tell you how good your CPU's performance is--but overall, it's a sweet little utility that Just Works. Looking forward to future versions!

(Note that I'm giving the app 3 stars for stability--it hasn't crashed on me, but that seemed to be the right place to downgrade it for the stalling progress bar and other rough interface issues.)  
(Version 2.1)

BCWINTERS  Lately I feel like Meteorologist has been stuck on its "endlessly searching for a connection" icon every time I look at it, even though the weather data looks up to date. I wish a little more maintenance development was going on to keep this great little menu bar item working well--many thanks to the commenters below who've linked to workarounds and patches, but this app needs more help!  
(Version 1.4.4)

BCWINTERS  If anyone is looking at the new screenshot for v2, please don't be scared away by the recipe display with the weird background and gold "frames" around each section. That thing looks like a Geocities page from 1997!

MacGourmet also comes with several clean, modern stylesheets--I use one that makes it look a lot like NetNewsWire, for instance. And they're all customizable HTML templates so you can make your own, too.  
(Version 2.0.1)

BCWINTERS  I recently upgraded from a great, perfectly-working version that was almost 18 months old so I could get FLV support. VLC's definitely my Swiss Army knife playback app.

The program remains robust and quick and makes it easy to float videos with a minimum of wasteful chrome. I use it constantly to play video on my TV while continuing to work in other programs on my PowerBook.

One downside is the complexity of the preferences--yes, you can tweak the app to your heart's content, but turning off all the On Screen Display elements that were added somewhere between 0.8.2 and 0.8.6 meant trips to three different sections of the prefs for me--and I still haven't figured out how to get rid of the scrub overlay that comes up if I tap Step Forward or Step Backward!  
(Version 0.8.6a)

BCWINTERS  I've tried a few times to abandon Eudora for greener pastures but other clients have always choked on several hundred megabytes of mboxes. This weekend I tried to make the switch to Mail.app again, this time using Eudora Mailbox Cleaner.

This time it was a success!

My many, many mailboxes made the transfer swimmingly although two (out of perhaps 200) were truncated and missing some mail. A quick re-import of those individual mailboxes and all was well. This could easily have been a Eudora issue (I was suffering from some mailbox corruption, hence the switch!) but bear in mind that if you use EMC you may have to do some manual checking to make sure everything is intact.

I had two other minor problems: although colors are imported in rule sets, existing colors/labels applied to messages are NOT transferred. And the "Rebuild Mailbox" Applescript choked about 3/4 of the way through my mailboxes and I had to do the remaining boxes individually by hand.

All in all, it took me about an hour to get everything set up perfectly in Mail.app while I'm sure it would have been MUCH longer without this great little utility. Don't even attempt to make the switch without it--but just make sure you check everything one last time before deleting your Eudora files!  
(Version 4.7.1)

BCWINTERS  Launches quickly with a double click and then all you need to do is type the time and hit enter. What could be simpler?

I end up using this almost every day. Inobtrusive, handy, tiny--a perfect little utility!  
(Version 1.4)

BCWINTERS  Works great. I'm using this utility to batch print PDFs from Virtual PC (which lets you route documents to your Mac printer but doesn't let you use any print dialog settings on the Mac side). Then I can send all of them to my real printer en masse at my leisure once I'm back in the office.

The "Label" setting to require unique PDF names in the outputted files is a MUST--see the reply to the previous comment for details on how to set it.

In practice I've found that the PDFs generated by CUPS-PDF are 3 to 6 times larger than those produced by OS X's built-in Print to PDF function but if time is at more of a premium than disk space, you'll find this utility very handy.  
(Version 2.4)

BCWINTERS  I could never QUITE give up iChat for the more feature-rich client Adium thanks to bothersome bugs.

Luckily Chax is here to bring an essential Adium feature over to iChat: tabbed chat windows! Awesome.

This is an utterly essential iChat plugin that I can't imagine living without--and I've only been using it for a few days.  
(Version 1.4)

BCWINTERS  I recently upgraded from version 2.3.0.4 to 2.4.0.2 and thus far I'm not incredibly happy with the changes.

Even when using the small fonts setting, this version requires wider columns to show the same amount of data than previous versions. I now have to scroll to see two columns that easily used to fit on my PowerBook's screen!

Double-clicking torrents in the Finder or in a Safari downloads window no longer opens the files (and yes, the file associations are set correctly on my Mac), although it does bring Azureus to the front. To open them, they must be dragged onto the app window instead, adding a tedious extra step. There's also an annoying file-opening "wizard" rather than a simple "choose folder to save in" dialog.

On the plus side, performance has improved (perhaps due to taking advantage of Apple's newer java implementation), especially in formerly lagging areas like viewing the list of files within a torrent to selectively choose what to download. Startup and shutdown are also quicker, and there are no longer stray processes left running when the app is quit.

I still can't help feeling like this version is in many ways a regression. But until I can find another client as stable as this with the same advanced features (per-torrent upload caps, peer-blocking plugins, selective file downloading within torrents), Azureus remains my go-to app for torrenting. It still gets high marks from me despite my complaints.  
(Version 2.4.0.2)

BCWINTERS  No problems using this in 10.4.3 over here.

I use this to convert Eudora mailboxes so they can be read by my server for Bayesian spam filtering. There are probably command line utilities that could be automated to do this, but LineBreak gets the job done in a quick, drag-and-drop fashion with no muss and no fuss. Just a solid, simple little utility that's handy to have around.  
(Version 2.6.1)

BCWINTERS  One of my most indispensible utilities from the pre-OS X days is finally back!

The "FinderPop Items" feature, which adds a simple Move To/Copy To/Alias To menu to the Finder's contextual menu has already saved me hours of shuffling files around in the Finder to keep my hard drive tidy.

Things are not 100% perfect with this latest version--like the description says, some features are still in development, and I run into a roadblock where the program wouldn't work after a reboot until I turned it off and back on again, but this is still a great utility with a bright future.  
(Version 1.9.9)