List The Free Games You Actually Play

Quake live

LoL,Cabal online,Bloodline Champions ( i used to) and now sometime tribes ascend Beta

1) - TF2

2) - Busty Hearts

3) - Crimecraft Gang Wars... but i dont like the last update...

i used to play Quake Live, but the chilean servers SUCKS; and the Argentinian ones, well, are down,up,down,up,down,down,up...

Crawl: Stone Soup, Spelunky, Wolfenstein: Enemy Territory, League of Legends, Heroes of Newerth, and eversion

From time to time I replay Command & Conquer or Command & Conquer: Red Alert.
Not on Steam, but really good RTSs anyway.

Octodad

Pirates Vikings and Knights II :)

Tribes: Ascend

League of Legends

League Of Legends

Look here: http://forums.steampowered.com/forums/showthread.php?t=851573

Buy Skyrim and be prepared to lose all your free time.

Voxelstein 3D - Surprisingly good recreation of Wolfenstein 3D using Ken Silverman's voxel engine VOXLAP. The visual style of Wolfenstein 3D really translates well to the voxel format and the levels are fully destructible.

I used to play War Inc, but we felt the game was so much boring after playing some CTF and deathmatch it was just not worth after a while.

Maybe that has changed with time....

I Wanna Be The Guy, Super Mario Bros Crossover, SD Gundam Capsule Fighter Online, Ace Online, Pokemon World, Need For Speed World.

Team Fortress 2. It's better than the vast majority of games that you actually have to pay for.

League of Legend,
Perfect World,
Lineage 2,
Pirate of the Burning Sea,
BattleStar Galactica,
Eve(is free but is hard in first mount :) )

If you're good at planning your character out ahead of time and you're good at PvP then you might want to try Allods Online. I say planning your character out because it costs money to respec and building your character wrong can make you weak in the end. Being good at PvP is pretty important because at around level 20 or so the area you go to for quests is a forced PvP area. Unfortunately, this second point is what ruined the game for me. It's a fun game (pretty much a Russian clone of WoW in most aspects), but once you get to that PvP area it can become almost literally impossible if you aren't good at it.

As for other things, pretty much just what other people have listed: League of Legends, Nitronic Rush, MMOs from Turbine or Cryptic, TF2, DC Universe Online, etc.

P.S. Do NOT play EQ2 if you're looking for a Free game. Although they do allow you to play free, you are extremely limited if you plan on playing that game without spending money (free players only have access to ~1/3 of the races and classes and worst of all, they can't even access all of their spells).

Eve Online
Faerie Solitaire
:D

Played LoL at one point as well as BLC, have TF2, currently playing DOTA2.

Global Agenda.
DC Universe Online.

Team Fortress 2, LoL, Super MNC, Ace of Spade
Only playing these at the moment. but there's also Alien Swarm, cant think of anything else right now.

Dwarf Fortress, obviously!

TF2..... Best Free game ever