I have a 2GB Corsair drive and I use a free program called "TrueCrypt" which has worked really well.
I also use the Portable Apps - USB versions of Firefox (browser), Thunderbird (email), and OpenOffice (MS Office clone) so anywhere I go, I can just plug in and have a browser with all my favorites, Office for doing documents / whatever, and I even have a super-small and thin Acrobat reader.
All these programs don't require anything to be installed on the machine I'm using at some internet cafe.
I also keep copies of my phone lists, passport, credit cards, insurance, etc, on the little encrypted partition in both .PDF and .TIF formats in case I ever need to print 'em out in an emergency.
Anyone have any other suggestions on what to keep on the USB drive when on the road?