madth3: Square Enix Publisher Weekend on Steam
Up to 80% discount on games.
(With a 85% on the Eidos Anthology)
Some really good deals here.
Tomb Raider (2013). $5.99 for GOTY, $3.99 for base game. I've recently finished this game myself and I can say this is by far the best Tomb Raider game as well the best action adventure game I've played. If you only buy one thing from this sale, buy this game.
Deus Ex games. $6.59 for all the games.
Hitman games. $7.99 for all of the games.
Dungeon Siege games. $4.99 for all of the games.
It's a shame the Final Fantasy and other Square Enix developed titles aren't more than 50% off. Would've loved a 75% off sale for them.