Gamefly has a good selection of titles on sale right now for 75% off plus an additional 20% off coupon.
http://digital.gamefly.com/#!/promotion/530 Use the voucher code GFDNOV20 (in UK GFDNOV20UK) for 20% off!
Some of the games include:
BioShock Infinite - STEAM - $5.99 20% voucher applied
Final Fantasy VII - STEAM - $3.19 20% voucher applied
Shadow Warrior - STEAM - $5.99 20% voucher applied
Torchlight II - STEAM - $3.00 20% voucher applied
Europa Universalis IV - STEAM - $13.99 20% voucher applied
Euro Truck Simulator 2 Gold $5.43 20% voucher applied
Scribblenauts Unmasked: A DC Comics Adventure - STEAM - $17.99 20% voucher applied
PixelJunk Monsters Ultimate + Shooter Bundle - STEAM - $6.71 20% voucher applied
Air Conflicts: Secret Wars $1.40 20% voucher applied
STALKER: Call of Pripyat $2.39 20% voucher applied
Jekyll & Hyde $1.59 20% voucher applied
Galaxy on Fire 2 Full HD - STEAM - $2.60 20% voucher applied
Air Conflicts: Pacific Carriers - STEAM - $3.00 20% voucher applied
Bridge Project - STEAM - $7.19 20% voucher applied
Thunder Wolves - STEAM - $3.19 20% voucher applied
Expeditions: Conquistador - STEAM - $7.19 20% voucher applied
Citadels - STEAM - $11.99 20% voucher applied
Air Conflicts: Vietnam - STEAM - $9.19 20% voucher applied
Adventure Park - STEAM - $12.31 20% voucher applied
Sniper: Ghost Warrior $1.59 20% voucher applied
Sniper: Ghost Warrior Gold Edition $1.80 20% voucher applied
Sniper: Ghost Warrior 2 - STEAM - $7.99 20% voucher applied
Sniper: Ghost Warrior 2 Siberian Strike - STEAM - $2.87 20% voucher applied
Alien Rage - STEAM - $5.99 20% voucher applied
Classic PC Games! - SAVE up to 80%