There's world-class surfing at Playa Encuentro, just outside of Cabarete (towards Sosua). There are several schools with surf shacks right on the beach or you can sign up for lessons in town...one company that has a shop in town and a shack on the beach is No Work Team. Also, there's Ali's surf camp which is kind of an all-inclusive for surfers in an area called pro-cab. Check out this site, there should be more info there:
Cabarete - Dominican Republic - by Active Cabarete