Mentioned on hotukdeals already, but Ubisoft are doing a promotion from today until Sunday where you can download a select PC game for £1. Games are:
Thursday: Hawx 2
Friday: From Dust
Saturday: Silent Hunters 5
Sunday: Driver San Francisco
Believe the games have to be downloaded with 30 days of purchase.
Other games are also on promotion on the same days, see following thread for more details: