One thing that's probably missing from your survival toolkit is a good chainsaw. You might have a small knife that will work in a pinch, but if you're looking for something with a bit more flare, Instructables user machoturtle has put together a guide for making your own pocket-sized manual chainsaw.
All you need is an old chainsaw replacement blade, a garden hose, gorilla glue and a couple of saws to cut down the blade. Cut down the replacement blade to a pocketable size, glue pieces of the garden hose on as handles, and you have a tiny little manual chainsaw you can take with you everywhere. Head over to Instructables for the full guide to make one for yourself.
Pocket Chainsaw [Instructables]