i joined bet365 for that purpose, you have to register and deposit at least £10 in to your account.
£10 is worth it just for the cricket but obviously you can use that money to bet with, i had a few small bets on the darts over xmas and am now up to £30 just through backing a few dead certs accumulating small amounts each time. Had £5 on Anderson to win PDC after his first round at 9/1 - gutted that one never came through, so close!
Thinking about putting the £30 all on Waites for BDO at 11/8, any thoughts?