I call my socket set Voltron. Not because I love the show (I do!) but because my current socket set is comprised of my five previous sets — I lose sockets constantly. But with the B&D ReadyWrench it's a physical impossibility.
You're not gonna lose sockets, primarily because the individual sockets are welded together into a hollow cube that sits at the either end of the wrench and rotates when you're selecting a size. It covers the most common sizes, 8mm-19mm. What's really cool is that each socket works for metric and its imperial counterpart, so the 8mm also fits 5/16". That means I've got essentially 16 un-lose-able sockets at my beck and call. It's also solid — it doesn't feel like it'd break it if I whanged on a rusty bolt or two.
There's no way to lock the selected socket in the down position, so the wrench will wobble slightly as you turn it, which makes it tough to really torque down on a stubborn bolt. Also the direction selector is a bit finicky — sometimes you can flick back and forth with ease, sometimes it'll just push the whole mechanism around. $US35 from Black and Decker.