Recent versions of AIM have no only include person-to-person text messaging, and chatroom test messaging, but the ability to share files peer-to-peer with your buddies [unlike Napster, and other peer-to-peer software, there is no directory of files, you only transfer files to one another as one would in an email], and to play games against one another [currently only avalible to Windows users]. All of your buddies are stored on AOL's servers, so you can talk to your buddies from any computer with internet access, provided you have the software, or even--- for those unwilling to download the software--- a computer that supports Java, thanks to AIM Express, a pop-up window in your browser that allows the basic functions of person-to-person text messaging.
The software is free, and is avalible for Windows, Mac, Linux, Windows CE, Palm and AIM Express is avalible, again for free, to anyone with a Java enabled browser.
To download AIM, or find out more information go to http://www.aim.com