If you want to go to Cuba, and are an American - I believe you might be able to go. There is a round Cuba cruise being offered - "Your Cuba Cruise?" - two departure points, Havana, hmm no for the US and Montego Bay! - so go to Jamaica and away you go.
I'm not sure about the passport control when on the boat, but I'm told its not an issue
Anyway, something to research if you really want to go

J&B