http://store.steampowered.com/?cc=uk
Front page:
Portal 2 -66% off £6.79
Duke Nukem Forever -66% off £5.09
Call of Duty: Black Ops -50% off £19.99
Orcs Muse Die! -75% off £2.99
Renegade Ops -50% off £4.99 ( 4 pack is only £9.99, = £2.50 each rather than £4.99 for a single game) - thanks to chaywa for spotting this!
Sam and Max Complete Pack -75% off £8.74
Test Drive Unlimited 2 -75% off £3.74
Dejobaan Complete Pack -50% off £7.49
The Oddboxx -75% off £3.24
Risen -50% off £7.49
Men of War : Vietnam -75% off £6.24
Mass Effect 2 -75% off £4.99
Highlights from sale:
Limbo 50% off £3.49
World of Goo -75% £1.75
Total War: SHOGUN 2 -75% £14.99
DiRT 3 -50% £14.99
Counter-Strike: Source £6.99
Garry's Mod £1.49
Left 4 Dead 2 £7.49
Dream Chronicles®: The Chosen Child***8482; £4.40
RAGE £22.49
Valve Complete Pack (lots of games inc. Portal 2, L4D2 etc.) -50% £24.99
Mass Effect -75% £2.49
Battlefield Bad Company 2 -50% £9.99
Dungeon Defenders -50% £4.99
Velvet Assassin is £1.24 - Thanks reejor04
Unreal Deal Pack - £5.74
Psychonauts, £2.99 - Thanks BlueDan
Nexus: the Jupiter Incident @ £1.49 - Thanks Quintus
Dark Sector @ £1.74 - Thanks Quintus
Source