The OSSwin project: Open Source for Windows!

* Audio editing tools
* Business Software
* CAD software
* Calendar Software
* CD Writing
* Compression/ZIP
* Databases
* Desktop Environments
* Dictionaries
* Drivers/Hardware
* Educational
* Emulators
* Encyclopedia
* Filesharing
* FTP clients
* Firewall & NAT
* File Systems
* Games
* Graphics
* Instant Messaging
* Internet Voice chat
* IRC clients
* Mail & News
* Media Players (audio)
* Media Players (video)
* Media Players (codecs)
* MC303 utilities
* Networking tools
* NTP clients
* Office tools
* Operating Systems
* PostScript viewers
* Programming
* Remote access
* Sciences and Math
* Security, Privacy, Protection,...
* Server software
* SCP (SecureCoPy) clients
* Stream Downloaders
* Text editors
* Utilities
* Video capture/processing
* VJ Software
* Web browsers
* Webcam
* Web editors
* Webgrabbers
* X-servers
* Others

http://osswin.sourceforge.net/