Mine is probably Geneforge. It really has everything I love in old school style RPGs, Unique setting, great story and excellent turn based gameplay.

My favoruite indie game is, be surprised, Aquaria. I just loved the graphics and the music. And the metroid like gameplay was worth any minute.

Close would be the Penumbra series and Amnesia :)

Play lots of them, some more, some less. But most of them I finish, and since I'm not a big fan of getting achievements, or completing 100% of the game on all difficulties, I don't really replay them. Like Trine, played it once. I liked it a lot, but once was enough for me.

What I do keep coming back to and playing from time to time it's Audiosurf. Play some of my favorite music, try to beat my previous highscores. It's fun and kinda relaxing.

Cave Story, it surprised me how good it was and it was released for free. I haven gotten the best ending yet because the last cave's difficulty is brutal and I'm not that good at it. I have Cave Story+ from the HIB too but I haven't started it yet.

Probably Zeno Clash. I don't play it "regularly", but I have replayed it a few times, yes.

For me it is Really Big Sky as i just lov the action and crazy gameplay (the music as well is great) Good for a quick change from rpg games.

Atom Zombie Smasher. Don't know what else I want in a game.

Minecraft with Better than Wolves.
And i recently got back to DoomRL, and boy do the tiles rock. ;)

Yes! I download it today for the first time and it is awesome. The music is brilliant.

Oh, of course! I forgot that Friction Games is still indie.

Yes, Amnesia and Penumbra are both amazing.
Is that still indie, too? It's done very well for itself, if so.

It's probably stretching the definition a little, but it's still more indie than not imho. It's hard to determine (if at all possible) where exactly a small independent development studio with a professional workflow and critically acclaimed output stops being "Indie".

I don't regularly play anything, except technically NWN because there's so much fan content. Once the game is beaten I don't replay it.

That said, I typically buy indie games in bundles and play to completion at least one of the games each time.

My favourite so far is Darwinia.
Braid is a close second, but since I beat it in a couple hours I consider it much too short.

Ah right, I completely forgot about creeper world. I played the demo of both of them and actually planned on buying them as well, but then I forgot about it. They're quite fun.

Mount and Blade Warband. Is Magicka an indie title? I haven't played it in a long while, specially since I reached a point that simply goes past my capabilities of staying alive. I also enjoyed Droplitz much more than I should have.