Can't lose on this really; worse case scenario is that you get your stake back. Best case scenario is, eg you place a £20 bet at say 33-1 and you pick up £660 + your stake.
Only downside of this is that it's for new customers only.
Basically - place a bet of up top £20 (and may as well be £20) and if you win you, well, you win. If you lose, well, you don't. You get your stake back within 72 hours. Just withdraw from your account then.
So, worth a punt on the World Cup - eg England to reach the semis/Brazil to win/ Holland players to fall out with each other/France get knocked out by their opponents handballing the ball into the net/Maradoonna failing a sanity test/ Torres to get injured in his first game all seem reasonable punts to me
CASHBACK ! - Register and go through http://www.thegamblingtimes.com
for £5 cashback (need to have a balance of £20 before you can withdraw).