Taken to its logical conclusion, if you legalize wagering on other types of contests involving physical skill or endurance, why not the traditional Atlantic City dance marathon?
Doesn't Bally's offer beer pong? I'm not sure how it works, but I've definitely seen people playing, and it seems organized by the casino for an entry fee.
OK, this is a free idea for any of you who can make it happen.
You get two of those arcade basketball machines and place them next to one another. In the middle is a kiosk that has bill acceptors and TITO (cashout voucher) printers on each side. The machine accepts $100 bills, one from each player and activates both machines when each player has put up $100. After the game, a ticket for $190 ($200 less $10 rake) prints out on the winning player's side.