It's just a simple lottery. I'm not going to get numbers from the real lottery because, to be frank, that's too much work.
I'll list winners as well as the amount they won and their address. I'm not sure on how the bitcoin network works yet, but can't you check to see if the BTC actually went to that address?
Example:
Say 9 people buy a ticket. You send some money to mybitcoin and back to a new wallet. You then buy 1 ticket. You then tell everyone you are using a random number but in fact you just send the winnings to your address. You post the winner and congratulate them and start another round. No one knows that you just paid yourself. There is no way to know if you did that or not. Bitcoin is kind of anonymous depending on how you use it and that's why HOW you pick the winner is important. Unless you design it such that you can't manipulate who wins, there is always that possibility.