If you take lots of photographs of small items, having a stand for overhead photography makes it much easier. Instructables user vkoudymov designed this wooden unipod to inexpensively do the job.
It's an easy build as long as you have access to a drill press. Essentially you're cutting a suitable piece of wood into various sizes, drilling holes, and assembling bolts with wingnuts. You'll end up with a a clamp that can attach to most tables and three adjustment points for your camera.
Hit the Instructables post for full details.
Overhead Camera Tripod [Instructables]