XAMPPApr 21 2005
Though it came out a few years ago, I just heard about XAMPP, a free package combining PHP, Perl, MySQL and Apache. It comes with PHPMyAdmin, FileZilla FTP Server, Webalizer and lots more.
The best part is, it's designed to be run on development computers. It installs into a single directory, and makes no changes to the registry or anything. It's perfect. I'm really impressed that this exists. I've always avoided working locally on my desktop, but now I'm going to give it a try.