Almost everything is on sale, including Tomb Raider, Hitman Absolution, Deus Ex: Human Revolution and pretty much every single Thief game ever made.
Tomb Raider -- the new quite good one -- is down to $7.99, Hitman Absolution is $6.24. But here are the best ones...
-- Thief II is $1.74 -- Hitman 2 is $1.74 -- Just Cause is $1.74 -- Just Cause 2 is $3.74
These are all pretty awesome deals, particularly if you're looking to plug some gaps in your collection.