MAHOJAS  The best application for managing my ebooks on my iPhone that I have seen so far. Praise for the developers for their work and constant updating.  
(Version 0.6.19)

MR650  Calibre is updated so frequently that discussing many of the bugs on MU seems almost pointless.

calibre is excellent for managing and viewing ebooks in drm free formats. After converting my books to epub I ran the server...and had to remove the epubs before 1900 (y2k python)...then I ran it again and had access to almost all my books from stanza running on my iPhone. To me, this is almost the perfect management solution.

The overall complexity of the interface makes this application a bit of a task to learn, but I have been able to enjoy reading and converting so many books with calibre that I think it is worth the effort.

I'm surprised at many of the low reviews and the 3 star average. I haven't seen any competing applications that are noteworthy, so what should this be rated on? For me this application fulfills the roles of ebook library management, format conversion, serving my network, and feeding my iPhone. It is the best at what I need and I think it deserves a lot more stars than are being granted.

If you have problems running the application, follow the directions in the comments for this application regarding downloading a new version and running that from your application folder.

My main wish for this application right now is a bug reporting system in the interface. This is a winner, but it's pretty beta (I haven't lost any files and don't expect to).  
(Version 0.6.4)

WOLFSMITH  This program is a huge help in bridging the gap between the sony reader and OSX. I don't understand why Sony decided they didn't care about making money from people who use macs, but with this at least you can import books purchased from other sites. It has a great conversion feature which translates just about any format into the LRF format.

What really sets this program apart is that the creator of it does it to help others and doesn't charge a dime for it. Whenever a bug crops up he tries to fix it as soon as possible.  
(Version 0.5.14)

PLASTERPYRUS  You know I never had any trouble with this applications. Yet there was a lot of criticism from a lot of folks that probably had something running on their machine that could have been the trouble. Anyway I hope that it gets some useful feedback since I personally haven't had much exposure to any other programs for this purpose.  
(Version 0.5.12)

MRGLSMRC  i can now recommend you try calibre because it runs on my machine without crashing, the code has been reduced by 40 per cent and adequate documentation exists on the web.

i will report how well calibre converts ebooks at a future time.  
(Version 0.5.12)

ZEPFHYR  I've been using this app for the last 3 or 4 point-upgrades and must say that I'm rather pleased with it so far.

It's not perfect, as I primarily use it as a way to get my ebooks onto my iPhone into Stanza and converting to ePub is a little hit or miss depending on the format you start with. But when it works, it works really well.

I only hope that future versions allow a manual table-of-contents or chapter creation subscreen. This would be of great use for those who are converting from PDF or other formats that exist primarily for purposes beyond ebooks.

While it's definitely got some ways to go, I can see this becoming the iTunes of ebooks in short order. Now, if only it can "auto sync" to devices like the Sony eReader.  
(Version 0.5.12)

GERRY CONWAY  I'd love to review this -- I'm desperate for a good Mobipocket-format ebook maker to run on the Mac -- but it crashes every time I try to open it and select a location for files. From one of the reviews below I get the impression there may be a webkit issue here? I'm running Safari Beta 4, and I've read that it screws up Mail in strange ways; is it possible it has an effect on some underlying functions in Calibre? No way to tell since the program won't even start up for me. Hope the developer manages to get this running sometime soon.  
(Version 0.5.11)

MRGLSMRC  i ran the program after the install. it hung and crashed as i was adding books. i can't be certain it is the programmer's fault because i use safari haxies and there's a lot going on here.

at over 100 meg it seems bloated and slow.

the documentary material about reader format conversion is non-existant on the programmers wiki.

i will wait for the next version and try again..

there's a lot of ebooks out there now and managing them is a good idea.  
(Version 0.5.10)

JOBBY  Why on EARTH does this need my admin password as soon as it runs?

No deal! Cmd-Q, Cmd-Delete.  
(Version 0.5.9)

THEBRIX2008  I have a Sony e-reader (PRS-505), which doesn't come with Mac desktop software and isn't supported by Sony UK - the official advice was to "use Parallels or Boot Camp to run the Windows software"! - but this application fills the gap superbly.

The Sony could be used without desktop software - it mounts in Finder as a drive, and .lrf files could be dragged into the appropriate folder - but caliber makes things easier and better:

1. Synchronisation between desktop and Sony e-book libraries, so the desktop library can be moved into a Dropbox folder and backed up that way;

2. Conversion of e-book formats, which is a lifesaver as .lrf is a relatively new format and there are many older e-books in (for example) .pdb format which, otherwise, would be unusable;

3. Editing of e-book metadata, including cover art, again another lifesaver as it is frequently wrong or mis-spelt;

4. (Best of all) Recipes, which scrape an RSS feed and bundle the content, including embedded images, into a .lrf file for synchronisation. There are now almost 200 recipes (100 in English), including all the main news and current affairs sites.

With the Sony Windows software, RSS feeds are not available at all in the UK and (I believe) are restricted to a small number of pre-defined sites (yuck) in the USA.

This is a great example of a "labour of love" which is better than the vendor's software; I have donated quite a bit to the author because it is so impressive.

The only omission is that Waterstone's e-book store cannot be accessed using Calibre. However, it uses DRM to protect its content, which is barely less expensive than printed books anyway, so I would not be interested even if I could access it; manybooks.net provides open content galore.  
(Version 0.5.3)