I can’t believe how many people don’t know about versiontracker.com. At this site you’ll find a link to the most current version of any software you’re using. Once there, you’ll select your operating system from a drop-down menu.
You can enter the name of the software you need a new version of, such as “AOL Instant Messenger” or you can enter “chat” or better yet, “chat client” and see a listing of all available chat clients for that operating system.
They currently keep track of Macintosh OSX and OS 8/9, Windows (all versions) and Palm software.