By using AIM you can just save the conversation whenever you want. But if you use a Trillian it will log all conversations you have in the program (AIM, Yahoo, MSN, ICQ, not sure about IRC). There might be specific applications that log AIM convo's but I am not sure.
I thought it might be a Mac thing. I guess that's one aspect i can finally admit that Macs have PCs beat. Either way i got me some trillian (and unfortunalty my fears of it being named after Star Trek are now stronger than ever) and i like its so far.
Could be from HHGttG i just vaguly remember (again as much as i am ashamed to admit it) an alien race on ST that could host other organisims within it called trillians. that seems like a pretty good description of the program. But in the end who the hell cares?
You could also catch some late night Pan-Polynesian Wrestling action every so often - it was the first time I saw Maniac Mark Lewin and I watched in drunken fascination as his "Crimson Mask" quickly became a "Crimson Bodysuit"...