I use youbet and to me it is by far the best. Excellent choice of tracks, good video/audio (if you have broadband), user friendly interface,fast deposit/withdrawal using their express feature, keeps your money in a trust fund, and is easy to qualify for no fee use ($350 handle per month or 2500 per year, I think). Also, it is a publically traded Nasdaq USA corporation.
Rebates are usually limited to harness races.
I don\'t trust the offshore rebate shops...as far as I can see you have no recourse if they decide they don\'t want to pay you.