Sites which I am or have been involved in

Great software

Opera The best web browser there is. Comes with everything built-in — mouse gestures, e-mail, news and RSS reader, etc.
Miranda IM Highly customizable instant messaging client (ICQ, AIM, MSN, etc.). Make sure you get the TabSRMM plugin.
Skype The program is ok, but what's really neat is SkypeIn. Why have a real phone when you can get the same features with Skype at a much better price?
Plaxo Outlook plugin. Keep your contacts, calendar, tasks and notes synced!
foobar2000 Audio player, highly customizable and great in all (?) ways.
Azureus BitTorrent client written in Java. Uses quite a bit of system resources but is full of features and has a neat user interface.
WindowBlinds Tired of what Windows looks like? Change it!
Xbox Media Center Turn your xbox into a great media player!
phpMyAdmin Great web interface for your MySQL databases
IISPassword Small and free ISAPI filter for IIS — lets you use .htaccess files for password protection. Even comes with a GUI.

Programming stuff

Haskell Awesome functional programming language
Nemerle Functional programming language for .NET
Download Opera