iChat AV has spell check
One quick item of note: Not only does iChat AV have great sound and wonderful video (been privy to both), but it has spell check. Yes spell check in iChat! I have been waiting for this for so long. It does not seem to be documented anywhere that I have found, but when I mis-type the words get a red underline, just like spell check in Safari, and I have the option of fixing.