The original “cool tool” was a multi-tool for the avid bicyclist. I’ve found the Crank Brothers to produce a superior version. I’ve used their Multi-17 for many quick repairs. Most often I grab the hex wrench to tighten a loose headset or seat. What distinguishes the Crank version from all other bike tools is its size, compact design and (very importantly) the included chain tool to remove a bent chain link. Few other multitools have a built in chain tool, and unlike so many other repairs, there is no way to ‘make due’ with another tool when you need to remove a bent chain link. Only a chain tool will do it. I spend many hours many miles from road (and water) mountain biking in the desert. I wouldn’t be without this gem of functionality.
[See the more recently-reviewed Multi-19. -- SL]