Play.com (rakuten) have an offer on, to promote their new website - a fiver off a ten pound spend.
I've just taken advantage to buy some xbox credit.
You could probably get one £10 voucher (costing £9.99) and add a filler item for a few pence if you can find one, to effectively get your xbox credit at 50% discount. I couldn't be arsed with that so just bought two £10 vouchers. Net result £20 of credit for £14.98.
Need to use code "SPEND10", which is good for new accounts only. If you did find a cheap filler item you could presumably use several different accounts to get loads of xbox credit for half price.
dealspwnShame they're posting the vouchers, rather than email. If they were instant I'd probably use them to buy DG2 tonight. But instead I'll get the vouchers at the same time as I get Zoo Tycoon and Halo MCC - so I'll probably just bung the credit on my account and leave it a few weeks before buying DG2.
There's a survey on xbox rewards this month, btw. 250 reward credits ain't worth much but it all adds up and I think it was only four questions.