An AOL Instant Messenger client. It's open source and still being developed (on Sourceforge). One of the best features is that it is only about 600k, and needs no installation, so you can carry it around on a floppy disk and run it on any computer you come to, for example at school. It uses the Oscar protocol, the official protocol used by the real AIM. It runs on Windows and Linux and was written by George Vulov.
-Portable: small size and no install necessary
-Tabbed conversation window
-Low RAM usage (10 times less than AIM)
-Buddy list availability sorting
-Offline messaging, which enables you to send messages to buddies who are not online, who receive them when they log on (provided by DoorManBot)
-Allows talking while away
-Can enable random IM coloring
Get it at http://terraim.sourceforge.net!