Adam mentioned something in the X2 thread that was interesting: He keeps a copy of Br@y Term on his flash drive. That's cool.
I read an article a while back in a photo magazine where someone was listing some of their travel tips for photojournalists. One was that they keep an installation of Firefox on a flash drive so that no matter where in the world they wind up, they'll have a browser that speaks their language.
I've got a flash drive! I even have two. One's got the source to my mini-sumo on it along with some g-code files for some parts I made almost a year ago. The other one is still in its original packaging, largely unused. You can tell I haven't quite figured out what to do with them.
So what do you keep on your flash drive?
I'd love to keep a live running copy of my AVR toolchain for Windows, but I'm almost certain that would be tough to do (so if I'm wrong someone let me know NOW!) I do tend to keep installers for things lying around, but that's not the same. It'd be even better to keep live environments for Windows, Linux, and OSX on the thing but now I think I'm stretching things.
A terminal program sounds like a good idea, as Adam pointed out (I'd never even considered that!) For reasons of my own VNC and Putty would be good.
But what else? Tools are tools, be they mechanical, electrical, or software. What tools would you keep in your pocket?