Of all my portable cycling-related tools, my multi hex-tool gets the most love. This thing is so useful that I don't leave home without it. Even when I'm not riding.
Here's what my hex tool and I did today:
1) Flipped my stem, tightening all headset / stem bolts
2) Raised my saddle a half centimeter
3) Helped a friend out whose saddle was coming loose from the seatpost
It's just like this, only a generic knock-off. I've had it for years and it has always been there for me. I love my hex tool!