I'm setting up a test environment for a patch management platform at work, so I needed to install obsolete (and frequently unavailable) versions of our most common apps. I ran across this site and thought I'd share it with everyone: www.oldversion.com. It has just about everything you could ever want, and most apps go back a loooooooong way. (Just be aware that if you use outdated software on a regular basis, you're exposing yourself to a host of security threats.)