MojoPac is a new product from RingCube that is essentially a virtual computer you install on a USB storage device (hard drive, memory key, iPod etc.). You can plug the device into any Windows XP computer and have access to all of your applications, games, documents, and whatever else you install on your MojoPac PC. Your MojoPac PC is isolated from the host machine, so that when you unplug, there is no trace of it being there.
I installed it on my iPod and played around with it a bit, and it shows a lot of promise. The basic install only took around 40MB of space on my iPod, plus whatever applications I installed. It wouldn't work on my Windows Vista machine, but that was to be expected.
Watch the demo of MojoPac from DEMOfall 2006.
You can download a 30 day trial version from the MojoPac website.