I don't frequently recommend individual products here, but this is so incredibly useful for anyone who builds, repairs or otherwise tinkers that I had to mention it.

The Mag-o-grip (not sure about the hyphenation) is basically a magnetic wrist-wrap that lets you keep nails, screws, nuts, bolts, drill bits and other useful metal things on hand. That's it - so simple I'm amazed it hasn't been around for 100 years, but I guess truly useful things are often this simple - and not really obvious until you see them. It's available for about $15 from MDG Tools and various retailers. I don't know about you, but I'm tired of having forgotten nails, nuts and heavy staples shred my shirt pockets and clog up the dryer lint trap...