Are you a serious DDR player? I'm not talking chubby West Virginian serious, I'm talking does your life basically revolve around Dance Dance Revolution? Also, are you handy? If you answered "yes" to both these questions, I've got a project for you.
Inventgeek has posted an absolutely massive guide to creating what looks to be an arcade-quality DDR deck, allowing you and a friend to Dance Dance to your hearts content without the condescending stares of Manchu Wok customers leaving the food court. The materials will set you back $400, and look to spend at lease 16 hours building it, but just think of how, uh, cool you'll feel once you get it all set up.
Ultimate Dance Deck 2.0 [Inventgeek]