Comment on Add-ons
iChat started as a very basic IM application. AIM, MSN and Yahoo could be said to have been ahead in some respects at this time
It could be said that iChat 1 and 2 lacked certain features that were available either on the major IM applications or as options run on other Clients, mainly those that could join several services such as AdiumX and Proteus on the Mac
The first four items were among the first Add-ons adding things like saying what iTunes was playing as the Status Message or adding the option to Add to your AIM Profile which iChat could not do.
These first four are known to be suitable for iChat 2 Only with the 5th stating it is iChat 2 only but I am sure it works in iChat 3 as well
In the ones 6 through 10 we see the emergence of Ecamm software. They were the ones that somewhat cornered the market on doing things with the basic video feed that allowed other cameras to work or as intended originally to allow the iSIght (external) to work on slower Macs. They also produced a setting tweak Add-On that works system Wide and not just in iChat.
The exception is iChat Streaming Icon that came out for iChat 2 but works in iChat 3 (I have not tried it in 4 as it has Animated Buddy icons. Edit 22nd Sept 2008. The site listed as Temporarily Unavailable
The ones from 11 - 14 are much more iChat 3 specific. Certain features of all of these are now included in iChat 4
Showmacster adds a pop out drawer that appears on the Preview or Video Chat window. It comes with about 20 or so Smiley type icons on one tab. You can drop pics you want to use regularly in other tabs. It also provide a Whiteboard option to the pics shown, do slide shows of groups of pics if preset in advance. It can be used to show all or part of your own screen as the Video feed. (iUSBCam can also do whole screen.)
ChatFX does things to the Video feed using Quartz Composer files. This is exactly the same as Photo Booth and the Effects in iChat 4. If you do not have iChat 4 the site has a series of Stills that are displayed on their front page. Unfortunately it does not work once you have updated to OS 10.4.10
Chax works with the other side so to speak concentrating on the User Interface of the Buddy List and similar options. Things like Tabbed Chats are now in iChat 4