I'll second Mark's recommendation for the Squirt. I have a Squirt P4, the model that comes with pliers. It's only 2 1/4" x 3/4" x 1/2", has pliers, knife, screwdrivers, bottle opener, file, etc. I work in an office, and it doesn't draw any unwanted attention. It fits in a pants pocket. I find that I use it almost every day for one reason or another. I'd hate to have to rely on it for long-term survival, though.