There are some decently priced Weekend deals and gaming releases on Steam at the moment:

• Play Unreal Tournament 3 FREE this weekend Plus Save 60% on UT3 Black or the Unreal Deal Pack.
• Garrys Mod is 50% Off making it US$4.99
• The excellent remake, The Secret of Monkey Island™: Special Edition is also 50% off with the same US$4.99 sale price.
• The second instalment of LucasArts titles is now available on Steam worldwide. You can purchase individually or just get the lot for $US 19.95
  The Jedi Knight collection includes:
  Star Wars: Dark Forces
  Star Wars Jedi Knight: Dark Forces II
  Star Wars Jedi Knight: Mysteries of the Sith
  Star Wars Jedi Knight II : Jedi Outcast
  Star Wars Jedi Knight: Jedi Academy