If you're into time-lapse photography and/or panoramas--or want to get started with them--and you have a camera with an intervalometer, Camarush's clever and inexpensive Camalapse mount sounds like a useful accessory to throw in your bag. Based on the same mechanical timer technology as a conventional egg timer, the Camalapse rotates up to a maximum of 360 degrees in one hour. You attach a small (less than 1 pound) camera or camcorder to its tripod mount, and optionally attach the Camalapse to a tripod, wind it up, and you're off and autorotating. You can also stack two units to achieve faster rotation rates.
Sure, you could build one yourself for lot less than the $24.99 it costs, but not everyone is blessed with the DIY gene. And it wouldn't be nearly as attractive.
You can buy the Camalapse direct from Camarush.