TWISTED  I tried it, I did not liked it - still searching for a better alternative to ScreenSharing  
(Version 2.6)

NEIL_M  I have downloaded and tried this, it works pretty well.

But it is $30 for a 2 machine license, not that cheap. I guess, a license @ $30 x 5 to make 10 seats, would be $150. I tried to find the cost for additional licenses on their website but couldn't.

A 10 user license for Apple Remote Desktop (ARD) is $299,

This version "kind of does" what Apple Remote Desktop (ARD) 1.0 could do, but ARD 3.0 is far beyond this or any other offering, in terms of features. So it's not worth comparing them.

I'm not even sure whether I'm convinced it is better than VNC.

•VNC is open source, cross platform and free.

•Additionally it is built right into OS X, authorisations are set in the same system pref, as Desktop.

•VNC uses the same ports as Apple Remote Desktop or Apple Remote Desktop uses the standard VNC ports, depending upon your bias.

•runs as in the background, being part of the OS

Transporter is an app, which you need to run on all machines.

Chicken of the VNC (COVNC) (http://www.macupdate.com/info.php/id/9517) - is an excellent VNC client for OS X.

•it is free

•it also uses Bonjour (zero config)

I use COVNC within my LAN and it is rock solid, I also use COVNC over a VPN and it also works well. A point to note is that Bonjour does not work over a VPN (without extra workarounds) so this feature is mute - you will need to plug in the LAN IP, for any of these apps.

• I don't see the option to manually input Ip addresses in Transporter - you can in ARD and VNC.

As per ARD, I do like the screen overview Transporter has, which VNC doesn't, but $30 I can live without.

I think this is a difficult niche for Transporter, on both sides you have 2 options both built-in OS X natively. VNC is free for unlimited computers, Win, Linux, OS X. ARD aimed at proper support and administration.

Overall I think Transporter has to really think about it's features - to justify it's license structure and price tag.  
(Version 2.0)

BLODWYN  1000gb! You have some serious networking bandwidth going there :-)   
(Version 2.0)

DANA SUTTON  A lot cheaper than Apple's Remote Desktop (which is priced for institutions and is exorbitantly expensive for SOHO use). Far easier setup than any similar shareware solution I've tested. I am using this to remotely access a 1GH G-4 over a 100gb ethernet connection, and although some operations (such as dragging and resizing windows) are slow, overall speed is satisfactory even with "millions of colors" selected (I'd be curious to see how this would work with a faster remote Mac and/or 1000gb ethernet). And I wish that the maximum window could be made larger, it's a bit hard to read text on the remote Mac.  
(Version 2.0)

SCHOOB  Tried it and it works, but for the money I'd rather use Haxial's KDX which does this cross-platform (mac controlling windows and vice versa) and so much more.  
(Version 1.2.1)

ANONYMOUS  This has worked fine since release. I tried VNC and it is harder to set up. The use of rendezvous make it easy to find other computers.

I had a small proplem and the author was very responsive.

Note: if it seems slow, use 15 FPS  
(Version 1.0.3)

ANONYMOUS  For a little more money you could just use Haxial's "KDX" which has the ability to control a remote computers screen (both Mac and windows) in addtion to lots of client/server features like file xfers, news, chat, private chat, DCC, msging, voice chat and it's all encrypted too.  
(Version 1.0.1)

ANONYMOUS  or go free with VNC  
(Version 1.0.1)

BUBBA  Not sure what Robert is trying to run this on but I ran it between a G4 and a G5 and performed very well. Exactly as expected!

I think it's a bargain at $15.  
(Version 1.0)

ROBERT WEISGERBER  Ok, I know it's only shareware, but I wouldn't even consider paying $15 for this program. I tried it between a 1ghz G4 laptop and a 1.6ghz G5 over a local network and it performed horribly. Save your money and get Apple Remote Desktop if you really need something of this sort.  
(Version 1.0)