Similar to the movie industry there are a lot of independent games that are produced out there. The challenge for me has been finding them - well, looking - I had a few bad experiences and gave up. The last few issues of PCGamer have had a section on non-mainstream games.
The first one I downloaded was Strange Attractors from ominous development. This is called a 'single switch game' in that you only use one key, the space bar, to move about. You control a small object with a gravity drive. When you enable your gravity drive you are pulled toward the largest gravitational element, and then the fun begins. You bounce, ricochet and spiral your way in and out of maps and traps. At its core its very simple and I've already lost a few hours playing it. A very nice change of pace.
Next was one that blew me away. I downloaded Babylon 5: I've Found Her, a completely freeware game set in the B5 universe. Before you go screaming off to another page, if you liked B5 and you like a real flight sim feel, this is for you. I could barely survive training. You are a Fury fighter pilot out flying cover, etc. I was blown away. The graphics, gameplay, and even the voice acting felt like any game I've bought at EB. If your looking for a challenge, pull it down. See if you over shoot the combat zone by 25k like I did doing 1.5k/sec. Oooops.
Finally, for those looking for a more leisurely game, check out Bonnie's Bookstore. I had the pleasure of being part of the beta for this game and got to watch it come together. This is a more traditional shareware game. The setting is Bonnie writing books with the game mechanic being you making words by connecting cubes in typical boggle fashion. There are power-ups, game changing tiles, etc. Just what you'd expect from a game of this type. I usually find myself playing this one while I wait to log-in to WoW.