Lord of the Rings: War in the North is on sale for $4.99 (75% off) at GMG. Th game uses Steamworks so Steam activation is required. If you picked up Greed: Black Border for free the other day, you could use your 20% off code to make it ~$4.
Men of War: Vietnam is on sale for $8.73 (75% off) at GMG until 1100 UTC 8/17. This one requires the GMG capsule program.
Rulers of Nations is on sale for $9.99 (75% off) at GMG until 1100 UTC 8/16. Use a voucher code to make it even cheaper. It requires their capsule program.
Greed: Black Border is Free from GMG for 24 hours. It might be for GamesCon. In addition, when you get the free game they’ll also give you a voucher good for 20% off at their store.
Velvet Assassin is on sale at Green Man Gaming (GMG) until Wednesday 11:00 UTC for $1.99 (75% off). This game requires the capsule program to play. BTW, there’s an unofficial list on the GMG forums by FreeMan85 of all the games that can be activated on Steam/Origin/GFWL/Uplay.
High School Dreams is on sale for $1.23 (75% off) at Green Man Gaming. I believe it’s the daily deal.
Dear Esther is on sale for $1.73 (75% off) at GMG. Use one of their available voucher codes to make it even cheaper. This is the Non-Steam version.
F.E.A.R. 3 is on sale for $3.84 (75% off) at Green Man Gaming (GMG). Use the voucher code PCGMR-GREEN-SUMMR to save an additional 20% off your order, which makes the game only $3.08. The game uses Steamworks so you’ll have to activate it on Steam. The 20% off voucher code expires on August 16, 2012.