The Portable Freeware Collection

Portable Freeware
Portable Means:

• It must run without installation.
• It must run on older versions of Windows which might not have been updated.
• It must not have any coupling with Internet Explorer, audio/video codecs, DirectX etc.
• It must not write settings to the registry or local filesystem.
• It must not leave any trace on the host machine at all, even when the app crashes (hereby referred to as "stealth").
• It must run with guest access rights.
• It must be able to compensate for USB memory stick drive letter changes.
• http://www.portablefreeware.com/
  

http://portablefreeware.com/forums/ is also a good place to go if you have trouble with any application. There are 1224 applications on this website.