IndieGames points out, sitting pretty atop the lists for both the US and UK is The Dishwasher: Dead Samurai developer SKA Studios' I made a game with zombies in it. Also known by its clinical title: I MAED A GAM3 W1TH Z0MBIES 1N IT!!!1.
Some other good indie fare is included in the list, along with Microsoft's almost instantly forgotten game-creator: Kodu. Yeah, remember that? Well, you can try the demo or download it for 400. Check out the full US list after the break, which could be different by the time this post goes up. The internet is fast.