Kennedy spent most of his time adulterating, and of course came very close to starting a nuclear war with the Soviets.
Cant remember anything great that he did, although he was cool, hip, trendy and charismatic. A bit like Obama.
That is somewhat unfair. It was the Soviets who pushed their luck, and the World to the brink of nuclear war, by sending ballistic missles to Cuba, just 228 miles from the southern tip of Florida. Kennedy actually held his cool and stopped short of pushing buttons. He also is credited with initiating the Washington to Moscow 'hot line' to inhibit the 'misunderstandings' that could occur between the two presidents and stop a future 'accidental' war.
In addition there is some evidence, although not much admittedly, that Kennedy was questioning the worth of the Vietnam War, with some planning to withdraw US advisors from South Vietnam in 1963, but his assignation put a halt to that and Hawk, LBJ, into office.............