I send my traffic to a few sites,
888casino
http://affiliate.888casino.com/?ag=279&pr=4999
Empire Poker
http://affiliate.empirepoker.com/?ag=279&pr=4999
Mad Bingo (if you have a market for middle aged women gambing on bingo)
http://affiliate.madbingo.com/?ag=279&pr=4999
And Peach Casino
http://affiliate.peachcasino.com/?ag=279&pr=4999
The nice thing is all of these are managed by the same company, so it's easy to track everything. I've never had a problem with getting paid. And I find them to be quite good at converting.
Let me know if you are looking into Poker rooms as well, as it's my primary gambling target, I have a lot of sweet deals.