I always have a leatherman with me. Can not need it for 6 weeks but when ya do need a screw driver, needle nose pliers, I am just glad I have it in the back pocket.
This dumb cheap thing has got me home safely more times then I can count. Walmart.com: Ultra Bike Tool: Bikes & Riding Toys
On 2 smokes, I carry every tool needed to build one. Really has served me well. Aside from the pull starts on Chinese 4 smokes, the bicycle it self is normally the difficulty at hand.
Cell phones are great! Bailed me out a bunch. Lets you take pics of the great stuff slow ridding can show ya and I use it to connect to the interweb on a mini-laptop