Free Portable Apps

PortableApps.com
A free take it with you versions of your favorite Open Source Apps.

UPDATE: PortableApps.com is worth a second look. There is now a great launcher called PortableApps Suite

From the Site:
What is a Portable App ?
A portable app is a computer program that you can carry around with you on a portable device and use on any Windows computer. When your USB flash drive, portable hard drive, iPod or other portable device is plugged in, you have access to your software and personal data just as you would on your own PC. And when you unplug, none of your personal data is left behind.