Steam has cut 33% off all Ubisoft titles with a new special deal every day until Sunday (50% off Rayman Origins today). It's worth noting that Ubisoft's catalog includes many franchise bundles, such as Splinter Cell's Elite Echelon Edition, which typically offer additional savings. Meanwhile, Amazon offers 75% or more off various titles, including a BioShock Dual Pack with the first and second games for only $7.49. GameStop has $20 off Skyrim, GamersGate discounts a slew of Kalypso  and Saints Row content, while Green Man Gaming celebrates its second birthday with 80% off Deus Ex: Human Revolution and Hitman: Blood Money.

Steam
88 Rayman Origins $14.99 (50% off)
76 From Dust $7.49 (50% off)
83 Anno 2070 $33.49 (33% off)
79 Assassin's Creed Revelations $26.79 (33% off)
89 Assassin's Creed 2 Deluxe Edition $13.39 (33% off)
70 World in Conflict: Complete Edition $6.69 (33% off)
79 R.U.S.E. $13.39 (33% off)
78 Driver San Francisco $20.09 (33% off)
80 The Settlers 7: Paths to a Kingdom: Deluxe Gold Edition $20.09 (33% off)
62 Silent Hunter Collection $26.79 (33% off)
81 Tom Clancy's Splinter Cell Elite Echelon Edition $30.81 (33% off) 
Tom Clancy's Ghost Recon Complete Pack $20.09 (33% off)
Shoot Many Robots $4.99 (50% off)
Far Cry Complete $13.39 (33% off)
The Heroes Pack $13.39 (33% off)
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Amazon Digital
76 ArmA2: Combined Operations $14.99 (50% off)
86 BioShock Dual Pack $7.49 (81% off)
79 Metro 2033 $4.99 (75% off)
72 Medal of Honor $4.99 (75% off)
83 Borderlands GotY $7.49 (75% off) 
87 Civilization IV: The Complete Edition $7.49 (75% off)
44 The Stronghold Collection $4.99 (75% off)
75 Serious Sam 3: BFE $9.99 (75% off)
80 Divinity II: The Dragon Night Saga $5.99 (85% off)
76 Battlestations Pacific $4.99 (83% off) 
82 Mafia II $7.49 (75% off)
76 The Last Remnant $14.99 (63% off)
65 Cities XL 2012 $9.99 (75% off)
Scarygirl $4.99 (50% off)
SimCity 4 Deluxe Edition $4.99 (75% off)
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GameStop
93 The Elder Scrolls V: Skyrim $39.99 (33% off)
47 Painkiller: Resurrection $4.99 (50% off)
Painkiller Black Edition $4.99 (50% off)
Painiller: Redemption $2.49 (50% off)
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GamersGate
83 Saints Row: The Third $24.98 (50% off)
68 Saints Row 2 $4.49 (70% off)
73 Cities in Motion Collection $13.58 (66% off) 
66 Dungeons Mega Pack $13.18 (60% off)
64  Disciples III: Renaissance $7.98 (60% off)
Disciples III: Resurrection $3.99 (80% off)
Dead Block $3.98 (60% off)
Medal of Honor Airborne $2.49 (75% off)
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GameFly
83 Torchlight $3.75 (75% off)

Green Man Gaming
87 Deus Ex: Human Revolution $5.99 (80% off)
71  Nuclear Dawn $12.37 (50% off)
63  Jagged Alliance: Back in Action $19.99 (50% off)
Hitman: Blood Money $1.99 (80% off)
Wasteland Angel $2.48 (75% off)
Sonic the Hedgehog 4: Episode 2 $10.94 (26% off)
Stellar Impact $4.97 (50% off)
Greed $9.97 (50% off)
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Games for Windows
84 Resident Evil 5 $9.99 (50% off)

GOG
50% off EA strategy/managerial games