Originally Posted by Socks

BetFair for sure man, I love that site. You can bet on sports matches for example at any time DURING the game... And you can bet on both sides... So for example let's say you're betting on a tennis match, Federer vs Anyone. Fairly even match, but Federer has a match point. If you put a few bucks on the guy whose about to lose, you'll get like 100:1 on your bet. If he survives the match point, the odds change a lot, back to normal. Then you can put money on Federer, and because of the odds differences no matter who wins the match you're guaranteed to make money.

Also you're not betting against the house, but other players.

Here's my ref code: CRC7YYPNG

Presidential election currently on betfair. Note: $4,754,327 already bet on this event on the site. ;)