For ATI/AMD (Radeon) graphic card users:
http://steampowered.com/ati_offer1a/
- Half-Life 2: Deathmatch
- Half-Life 2: Lost Coast

For Nvidia (GeForce) graphic card users:
http://steampowered.com/nvidia/
- Half-Life 2: Deathmatch
- Half-Life 2: Lost Coast
- Portal: First Slice

For all Steam users:
- Alien Swarm
- America's Army 3
- BattleForge
- Between
- Champions Online: Free for All
- Codename Gordon
- COIL
- CrimeCraft: Bleedout
- Global Agenda: Free Agent
- Mightier
- Moonbase Alpha
- Peggle Extreme
- Puzzle Pirates
- Sam & Max Episode 104: Abe Lincoln Must Die!
- Spacewar
- Spiral Knights
- Team Fortress 2
- The Cat and the Coup
- TrackMania Nations Forever

For regional Steam users: (aggressive IP Block)
- Alliance of Valiant Arms
- Forsaken World
- War Inc. Battlezone

Free addons and resources for already purchased games:
- Half-Life (high definition models)
- Post Apocalyptic Mayhem (Death Area 8 DLC)
- RACE 07 (Crowne Plaza Raceway track)
- Railworks 2 (Billionaire Benefactor Scenario DLC)
- Railworks 2 (Keeping Up with the Diesels Scenario DLC)
- Railworks 2 (Off the Cotswold Line Career System Scenario Pack DLC)
- Railworks 2 (Port Road Expansion Pack DLC)
- Railworks 2 (UK Buildings Model Pack DLC)

Steam delivered MODs:
- Age of Chivalry (requires Source SDK)
- D.I.P.R.I.P. Warm Up (requires Source SDK)
- Darkest Hour (requires Red Orchestra)
- Defence Alliance 2 (requires Killing Floor)
- Dystopia (requires Source SDK)
- Empires Mod (requires Source SDK)
- Eternal Silence (requires Source SDK)
- INSURGENCY (requires Source SDK)
- Mare Nostrum (requires Red Orchestra)
- Pirates, Vikings, and Knights II (requires Source SDK)
- Smashball (requires Source SDK)
- Synergy (requires Half-Life 2)
- Zombie Panic! Source (requires Source SDK)

Related stuffs:
- BioShock: Breaking the Mold [Art]
- Company of Heroes: All Heroes Rise OST [OST]
- Company of Heroes: Songs From the Front OST [OST]
- Garshasp: The Monster Slayer Art Book [Art]
- GREED: Black Border OST [OST]
- Warhammer 40,000: Dawn of War II OST [OST]
- Zombie Movie [Mac/Win][Mov]

Honorable mentions:
- Portal 2 Soundtrack: Volume 1 [OST]
- Portal 2 Soundtrack: Volume 2 [OST]

Link en los foros de steam: http://forums.steampowered.com/forums/showthread.php?t=851573

Para instalar las cosas: Tienen que tener abierto steam, y en el link de los foros de steam que esta mas arriba, hacen click a "install" y comenzara a bajarse la wea que quieren de la lista

eso, es viejo pero no esta de mas ponerlo.
ojala les sirva a los "pceros" para que tengan muchos juegos y BUENOS, de manera oficial =)