Portable Firefox

The Tablet PC Weblog has a post about this customized version of Firefox that is designed to run specifically from a USB flash drive.  This is super-useful if you tend to use other people's computers a lot or travel to other offices where it is not practical to bring your laptop and you don't want other users to be able to view your browsing history.  For consultants or people that work at client locations, this is useful for using client machines to browse the web.  The download is free and it supports Firefox extensions; 0.9.3 is billed as the "stable" version and 1.0PR is billed as a "test" version.