For this year's Grand National I came across a deal with Coral; bet £1 get £30 in free bets (3x £10 bets) for new customers.
Free bets are valid for 4 days. (I'm using my free bets in the Grand National too.).
£5 minimum deposit.
I know not everyone likes gambling, or The Grand National, but thought I would post this for those who may use it.