These are taken from the motherforums, but since a lot of people don't check there I thought I'd transfer them over.

XBOX @ Currys/Dixons



If you check Currys out you (so I'm told) get a voucher for £15 off as well. I've not seen the evidence of this but its worth a butchers if you're in the market for an XBrick.

Gamecube



The Gamecube offer is available at most stores once MarioKart is released.