GOG.com is having sales for the next two weeks, they choose two games and people vote on which one gets a 60% discount and which one gets a 40%. I got Indigo Prophecy (Fahrenheit) for $2.99 a few days ago. They are one-day sales, so you have to be quick, but some of the games are insanely cheap.
Limited selection, but most of the games on GOG are pretty good. Where else would I find a bunch of pre-configured 90s FMV games?