Best Indie games on steam?

killing floor

so far, Space Pirates and Zombies (SPAZ) is the indie game i've had most fun with

Time fcuk (you can play it for free at Newgrounds) , The Binding of Isaac, Super Meat Boy, Braid, Limbo and Dungeons of Dremor

Isaaaaac

Trine one and two are the best indie games I've ever played, and probably the best two games to come out in the last 5 years or so

Zen Bound 2,
VVVVVV,
World of Goo,
Fortix (2),
Osmos,
Titan Attacks,
Chime

Amnesia, Sanctum, Dungeons of Dredmor, The Binding of Isaac

FORTIIIIIIX

Braid

Amnesia and Trine definitely

Very good, but not yet mentioned:

• Aquaria
• Vessel
• SpaceChem
• Q.U.B.E.

Tribes Ascend

Orcs Must Die!

Team Fortress 2

Indiana Jones and the Fate of Atlantis badum tss

Offspring Fling! and Serious Sam series :)

Orcs Must Die 1 and 2, Dungeon Defenders, Binding of Issac, Super Meat Boy, Penny Arcade's On the Rain-Slick Precipice of Darkness 1-3

Recettear: an Item Shop's Tale - superb business and resource management sim with an action RPG sub-game.

Terraria - excellent world-building game with online co-op play mode.

• Super Meat Boy might be the best game I've ever played. (Civ 4, Mother 3, and Deus Ex compete)

• Dungeons of Dredmor has endless varied dungeons.

• Bastion is almost as good and has excellent storytelling with simplified diablo-esque gameplay.

• Terraria is better than Minecraft.

• Frozen Synapse is the pinnacle of tactical multiplayer.

• Limbo is surprising and emotional.

• Gemini Rue has excellent storytelling and is future noir.

• Space Pirates and Zombies (SPAZ) is the best thing since Elite if you prefer fun to realism.

Amnesia!

Tiny and Big

Awsomenauts!

Super Meat Boy. I'm just sad that they don't bother implementing Steam Cloud even if it's almost vital for a game like this, nor fixing the random lag that happens once in a while, and always at the wrong time obviously. An anti-cheat mechanism would have been a nice addition too.
Without these issues, the game would be almost perfect in my opinion.

Also, Trine 2 and The Misadventures of P.B. Winterbottom (I don't know if this one can really be considered indie though). Insanely Twisted Shadow Planet is nice too.
I would also gladly have added The Binding of Isaac to this list if it was programmed in a less shitty language...

Bastion, Awesomenauts, Caster!!! Makes you feel so powerful!

Recettear, RUSH/Edge, Wanderlust: Rebirth, Dungeons of Dredmor, Spectromancer, Ticket to Ride, Tidalis, Altitude, Audiosurf, Plain Sight, SpaceChem, HOARD, Flight Control HD, Flotilla, and AaaaaAAaaaAAAaaAAAAaAAAAA!!! for the Awesome.

Penumbra, Limbo, Braid, Machinarium.