You basically play mini-games for free, and you make money if you win. You start small and double each time you win. Win 30 times in a row, get 10 million. You can cash out at any time. And hell, it's free.
I just set up 3 yahoo email accounts, and made sure I changed my address a bit. For example, instead of Ave, I wrote Avenue; or West instead of W. On true, I did the same thing, but I did use the same card every time.
Good Luck!