iOS/Android: Be prepared for the worst case scenario with this free app based on the US Military Survival Manual. Survival Guide's 19 chapters of tips and techniques teach basic fire principles, how to deal with dangerous animals, how to survive all kinds of harsh environments and much more.
The text and illustrations are available offline, so if you ever find yourself adrift in the open sea or in a leech-filled swamp, you'll be able to look up what to do.
Although the guide could use a bit more emphasis on the tips parts, which are buried in the overall descriptions of each danger, the guide is very detailed and thorough. It's a potential lifesaver (and might make you more like the character Anthony Hopkins played in the movie The Edge instead of Alec Baldwin's).