rock, paper, sissors is suitable for a simple form of gambling, but the ties slow things down.

It is better if each side chooses a number. If the number sum to even, then person A wins. If they sum to odd, then person B wins.

Maybe person A will try and say his number slightly late, so that he can listen to B and cheat.

To avoid this, both parties should write down the number they chose, and then show each other.

or equivalently, they trade hashes of the number they chose first.

This is a very simple case of

http://en.wikipedia.org/wiki/Distributed_computing distributed computing.

I have a plan on how I can use this to build a trustless distributed poker system.