http://www.leapsecond.com/pages/chess/ as seen on Engadget and BoingBoing.

Ingredients
50 ohm BNC, SMA, and N terminators with various BNC, SMA, N, APC7, F, UHF connectors and inter-series adapters; or any other RF connectors you can find around the house. White gets nickel or stainless steel and black gets gold top pieces. p.s. Dad lost the first game.