I am wondering the same thing. I just read through and posted on another thread on the same topic. There are some interesting ideas there:
http://forums.tigsource.com/index.php?topic=29257.0We are about to release a game on Desura. When we released it on Xbox Live Indie Games we emailed a lot of the blogs that covered XBLIG games and some that did not. We ended up getting a good number of reviews and some nice reviews, but it did not really translate into sales at all. I have heard that XBLIG is weird like that, (I cannot say about other stores/platforms, it was our first game, so you may have much better success with reviews generating sales), but I am trying to think up ways to get people to know about the game outside of reviews.
One idea I had was that you could give the game slightly cheaper if ten of the person's friends put in a redeem code. Like MMO's, where they give bonuses if you spread the game. Just thinking...
I like the idea of giving away/reducing the cost of the game if someone helps raise awareness. Even if it does not increase sales much, creating a fan base is probably great in the long term to help with sales and promotion.