"For most people, mobile computing means a laptop. Some make do
with a Linux live CD distribution such as Knoppix and a USB pen
drive to save their data, or one of the newer live CD distros that
run off a rewritable CD or USB drive, but if you can't restart the
box where you end up, those won't help you. Now, thanks to John T.
Haller's PortableApps project, you get to use your favorite open
source productivity applications from a USB drive without
restarting a Windows-based host computer.
"On the project's Web site you'll find several portable
applications: Portable VLC player (audio and video player),
Portable NVU (HTML editor), Portable Firefox (Web browser),
Portable Gaim (instant messaging), Portable Thunderbird (email
client), Portable AbiWord (word processor), Portable OpenOffice.org
(office suite), Portable GIMP (image editor), and several others,
each with a dedicated support page and forum..."