A quick post to highlight this very useful application.
My work computer is administrator locked - not usually a problem, except I'd much prefer to use Firefox instead of IE. If, like me, you prefer to enjoy the benefits of tabbed browsing and pop-up blocking, then you know what I mean.
This version of Firefox runs off a thumbdrive (30-something MB of space needed) - which is exactly what I'm doing now. Nothing needs to be installed on your computer, which gets around needing administrator access. Your bookmarks and preferences stay on the thumbdrive, so you can bring them with you if you move between computers at work and home. This is possibly the most useful thing I've seen this whole year.
There are still some problems getting it to work with Macs (detailed on the page), requiring some manual editing of the files, but I already have Firefox installed on my iBook at home anyway. This just means I can now bring it to work with me.