Amazon's Cyber Monday sale is stretching out over the whole week, allowing bargain-friendly players an opportunity to capitalize on the company's generosity (and/or unawareness of what constitutes a “Monday”). Today is the sale's PC Games Day, with 40-75% off the download price of some no-fooling AAA titles; there's also some lightning deals so limited that you might actually miss out on them if you finish reading this sentence. Too late (maybe)!
Notably large discounts in the PC sale have Metro 2033, S.T.A.L.K.E.R, Amnesia: The Dark Descent and the original Darksiders at 75% off, and The Witcher 2 discounted 60%. The half-off tier of the sale sees Deus Ex: Human Revolution, Alice: Madness Returns, and Dead Island going for 50% of their usual price – a discount that also applies to the boxed versions of Super Street Fighter IV, Dungeon Siege IV and Dead Rising 2: Off The Record. You can also get 40% off the Complete Edition of LA Noire or the Game of the Year version of Civilization V, whether you want the convenience of a download or the satisfyingly environmentally-unfriendly sensation of holding a real box in your hands.
If you're both quick-witted and strategically gifted (descriptions which 4 out of 5 PC gamers would agree apply to themselves), there's also lightning deals on plenty of new titles. At time of writing, deals include Call of Duty: Black Ops, Duke Nukem Forever and Warhammer 40K: Space Marine, but check the site to see which hourly specials take your fancy.