Humble Bundle has some great games being offered cheap now.

Goto their site to see what they have, the current good one (in my opinion) is the Card Games one. Has a bunch of digital card games, some Steam and some not-steam, including Magic 2015 and the expansion.

Also Origin had Theme Hospital for free. Not sure how much longer, or even if that is still free, but Origin usually is worth checking regularly since they offer games for free on a regular basis.

A site someone in our group pointed out to me (fast2play) offers games at inexpensive prices. I purchased Sins of a Solar Empire Rebellion on there for $8 and change (on Steam it was listed at $39.99). So for my one purchase they were a legitimate site.