We love a good keychain tool around here, and the stainless steel DoohicKey by Nite Ize is about as classic as it gets. It's at least half a dozen handy tools in one:

1. Three-sized hex wrench (¼", 5/16", and ⅜")
2. Etched ruler (imperial on one side, metric on the other)
3. Bottle opener
4. Flathead screwdriver
5. Pry tool
6. Box cutter

Can't ask for much more than that! Oh, and did I mention you can pass through TSA checkpoints with it, no problem?

Get the DoohicKey for just $7 on Amazon.