Copy Adium's options for IM style. For example, Adium will let me do something like this in its preferences:
(01:09:12)<Joe> Hey, dude.
(01:09:15)<Me> Hey, how goes it?.
(01:09:19)<Joe> Pretty good. What'cha up to?
(01:09:25)<Me> Oh, I'm just bitching on the SourceForge boards about how Fire needs to copy Adium's IM style options.
(01:09:27)<Joe> Oh, yeah, totally.
Obviously, with the option to not include the timestamp, or to build up more things, like including the screenname too, if you want to do that. I like the faux-IRC look that I can give to AIM by using angle brackets.