USB drive is master, and laptop is backup.

Several applications (such as thunderbird) are now on USB drive. Along with working data. So USB drive is now a master and your laptop harddisk is a slave! True inversion of roles!!

You can probably use a program such as unicorn to do the backup. (Need to check if it is USB friendly.) And you even have advantage of using your home computer as second backup.

Indeed, an inversion of roles!!

BTW, I actually like SD card rather than a long thumb drive. These can be inserted into a laptop (via a PCMCIA card, or a slot itself if laptop has it), and so they don't protrude out. Keep a SD-to-USB adapter around in your laptop back.

(Triggered by pcmag: Ultimate USB Key) that lists a lot of useful apps.)

-Vinod