Here's a nifty thing I first read about in Web4Lib: portable apps ! These are downscaled versions of common applications like the Firefox web browser  or Thunderbird email client  that are small enough to store (and take with you as you travel) on USB flash drives, iPods, or other portable hard drives. What's extra great is that NOTHING has to be installed on the computer you plug your USB flash drive into - it all lives on the portable drive! Here is a list of some of the software  currently available. All portable app software is open source, so there's is no cost to download and use it.