In honor of QuakeCon 2011, Steam is running a Bethesda promotion starting today and carrying through Sunday. It's better if you just go to the landing page for this sale event rather than have me list everything, which would be ridiculous. I will point out that for this weekend, Brink is free to download and play.
Today's deal is the Doom and Quake Complete Pack for $29.99; pre-purchase Rage, and you get an extra $10 off. For us Team Fortress 2 players, there's a bunch of new items related to the on-sale franchises. These are tied in with game purchases, so if you grab Fallout: New Vegas, for instance, you get a f**king Pip Boy for the Engineer.
I rarely even play the Engineer and I'm about to go through with this transaction. The Quake Rocket Launcher for the Soldier that comes with Quake IV purchases is also highly tempting.