I'm in the process of creating a "Mobile PC" using a 1GB USB key and my favorite applications. When I'm done I'll put the entire key on the blog for a free download. The plan is to have a USB key which I can use on any computer and still have all my favorite browser (and favorites), email etc. - If you think this sound interesting take a look at http://opera-usb.com/ and http://portableapps.com/
The above screenshot is Opera@USB v9.25 - The browser runs entirely from the USB key, no install or any other footprint left behind on the host PC.