Nice thread, Red. I've been meaning to make this thread too, cause I've been doing some indie gaming myself.
Note, When I say indie, I mean not published by a retailer. That is, these games are usually free to download and play.
I start with TAG: The power of Paint.
It'a a fairly simple concept. A puzzle based First Person Platformer, much like Portal (If you haven't played portal, go do it now. I cannot stress this enough).
You basically have a paint sprayer gun, with an unlimited amount of paint in 3 colors, and a grey environment full of buildings and roads that you can paint with the spray gun. The colors have special effects when you walk onto an area that they're sprayed on.
Green-makes you bounce when you step on it.
Red-Makes you increase speed as you run on it (Makes the surface low friction, basically)
Blue-Allows you to stick to that surface.
you use these tools to your advantage as you navigate.
It's made by students from the DigiPen Institute. In fact, several games from that above site count as fun to play indie games, though some of them may be less fun than initially advertised (Rydenstyke, from the above site, made by a different group of students is pretty dull, and I was expecting better)
Anyway, these guys who made TAG- They're now working on a little game called Portal 2, and they're making new game mechanics for it. Good for them