Yeah, there's a ton of things to do (Besides baseball).
Broadway shows, museums, usual tourist stops like Empire State Building, Ellis Island, Statue of Liberty, Battery Park, Central Park, Wall St., Little Italy, Chinatown, Times Square, USS Intrepid, and the 9-11 sight.
Then there's night life. Great restaurants, variety of different bars and clubs (close at 4AM).
Really depends what you're into. NYC has everything.