It's tough to beat the little swiss army knives when it comes to a keychain knife. They're pretty much a perfect combo of size to features, and they're unobtrusive enough that you can take them just about anywhere.

My favorites are the Swiss Lite (basically a classic keychain swiss army knife that has the toothpick switched for a little flashlight) and the Midnight Manager, which is a rambler with a flashlight and pen instead of tweezers and toothpick.


Leatherman's Squirt series is also really good, with the P4 being my favorite.

Another neat little keychain knife is the Buck Metro LED. Locking blade combined with a small flashlight. This is one of my favorites to give as a gift.

It's also worth noting that Doug Ritter, along with CRKT, has a small fixed blade that one could put on a keyring. The RSK Mk5. It's bigger than your average keychain tool/knife, but it's also capable of taking much more abuse.