http://www.electricquarter.com/contadapt.htmVERY useful for console emulation on your PC.
Some of them are fully compatible with DDR and Stepmania games as well (the newer PS2 adapter, and the dual adapter being best for this)
Also check out my ebay store for newer lower prices since I've been moving my classic videogames to my ebay store instead of auctions, dropping the price drastically.
http://stores.ebay.com/The-Electric-QuarterPlease remember, if you don't have anything nice to say, don't bother.