In an unprecedented accomplishment, Games For Windows Live has what may very well be the best deal of the weekend, though it doesn't kick off for a few hours:

Games For Windows Live (Client)
• Batman: Arkham Asylum - $12.50 (75% Off)
  Price valid Friday, February 26 through Monday, March 1

Steam
• King Arthure Pack - $28.80 (33% Off)
• SpellForce Platinum - $3.74 (75% Off)
• SpellForce 2: Gold Edition - $7.50 (75% Off)
  • SpellForce 2: Shadows Wars Exp. - $4.99 (75% Off)
  • SpellForce 2: Dragon Storm Exp. - $4.99 (75% Off)

Direct2Drive
• The Best of Indie Bundle Vol. 3 - $29.95 (75% Off)
  World of Goo, Puzzlegeddon, Gish, The Maw, Braid, Cogs, Aaaaa!, Osmos, Machinarium, Crayon Physics Deluxe

Impulse
• Battlefield 2 Complete - $22.49 (25% Off)
• Evochron Legends - $18.70 (20% Off)
• Eufloria - $13.99 (30% Off)
• Mount & Blade - $5 (80% Off)
• Project Aftermath - $4.99 (50% Off)
• Space Rangers - $6.99 (65% Off)
• THQ Ultimate Bundle - $99.99 (Usually $344.83)
• Tropico Reloaded - $4.99 (50% Off)

GamersGate
• 18 Wheels of Steel: American Long Haul - $8.49 (50% Off)
• Aztaka - $12.49 (50% Off)