To kick us off, they're offering these deals:
- Peggle + Peggle Nights: 60% off - £5.59
- Deus Ex + Deus Ex Invisible War: 85% off - £1.49
- Fallout 3 GOTY Edition: 33% off - £13.39
- FEAR Complete + FEAR 2: 75% off - £5.74
- Super Meat Boy: 75% off - £3.00
- All Prince of Persia Games - 75% off
- Lego Batman: 75% off - £2.49
- Portal: 75% off - £2.49 (or 85% off - £1.50 if you own HL2)
- Titan Quest Gold: 75% off - £2.49
- F1 2010: 50% off - £14.99
- Battlefield: Bad Company 2: 66% off - £6.79
- All Oddworld Games (Including newly released Munch's Oddysee and Stranger's Wrath): 50% off - £9.99
Obviously, there will be different deals each day, and there are a slew of publisher catalogues that have big discounts as well. Head over to the Steam website to see what they're offering right now.