Maybe you can add a Blackjack game in the Gaming Center. Have people choose a certain amount of coins to bet before the hand starts. Since it'd be very difficult to have multiple players play at the same time, maybe it can just be a player and the dealer (CPU). You could even use the card algorithm that determines the random cards provided in "High/Low".

Using conventional rules of blackjack, if the user is to win, they'd get receive the amount they bet. If the user loses, they'd lose the amount they bet.

Maybe make an minimum on the coins that can be bet (10 coins, maybe)? Just thought it would be interesting to see something like this implemented, and a more fun way of gambling coins.