I didn't check other cities, but tickets from JFK to Samana, Romana, Santo Domingo & Puerto Plata are all on sale for a month if you buy tickets by tomorrow. For example, JFK to SDQ is $209. Caveat --- the sale prices don't seem to apply for the return trip to JFK, though it was only $227 in the few itineraries that I tried.
JetBlue | The Book-Smart Sale
JetBlue | The Book-Smart Sale