With Mass Effect 3 coming next month, it's a great time to catch up with the series and GameFly (formerly Direct2Drive) is selling the second installment for only $4.99. Microsoft is offering some legitimate discounts this week with 50% off Square Enix/Eidos games, including two old school Deus Ex titles, Thief: Deadly Shadows as well as Hitman 2 and Blood Money. Meanwhile, Steam is practically giving away PopCap hit Plants vs. Zombies and GameStop has 50% off Bastion. As a side reminder, the latest Humble Indie Bundle ends in four days and a fifth game, Toki Tori, was added this week.

Steam
90 Plants vs. Zombies GotY Edition $1.99 (80% off)
44 Stronghold 3 $24.99 (50% off)
46  Call of Juarez: The Cartel $16.99 (66% off -- today only)
Star Wars Jedi Knight Collection $4.99 (75% off -- today only)
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GamersGate
Ground Control + Expansion $3.00 (50% off)
Ground Control 2 Special Edition $3.00 (50% off)
Metacell $4.99 (50% off)
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Games for Windows
Battlestations: Midway $9.99 (50% off)
Conflict: Denied Ops $9.99 (50% off)
Deus Ex: GotY $4.99 (50% off)
Deus Ex: Invisible War $4.99 (50% off)
Hitman 2: Silent Assassin $4.99 (50% off) 
Hitman: Blood Money $7.49 (50% off)
Thief: Deadly Shadows $9.99 (50% off)
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GameFly
93 Mass Effect 2 $4.99 (75% off)
72 Medal of Honor $4.99 (75% off)

GameStop
89  Bastion $7.49 (50% off)
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Green Man Gaming
52 The First Templar $21.79 (27% off)
75 Two Worlds II $31.99 (20% off)
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Good Old Games
50% off various TopWare games