Card Games for Three Players?
I think one of the best card games for three players is Skat (not to be confused with the Scat mentioned in another answer). This is a pretty heavy game on the level of Bridge, so you can decide whether it's a good fit for your group.

I personally prefer Ninety-Nine which is like Oh Hell! with a really funky bidding technique.

You might also find this list on pagat.com helpful. It seems like the numbers outside square brackets are the recommended numbers of players.