It's about 35 minutes by train from JFK to Penn Station, which is in Midtown (this is via the Long Island Rail Road, so no worries about sketchy subway stops). From there it's an easy walk (2 blocks) along 34th St. to the Empire State Building if you want to get a quick view of the city. On the way you'll pass Macy's, the world's largest store. You could also head up to Times Square, which is particularly impressive at night, with all the lights--it's just a 10-15 minute walk or one stop on the subway. Of course there are many other things to do in Manhattan--fantastic museums and beautiful neighborhoods--but these are just a few things that are easily accessible on a quick excursion from JFK.
If you're less interested in seeing the big touristy sights, you could also just go get a good dinner somewhere, since you won't be served food on the plane until well after midnight, and with 7 hours to kill, there is NO excuse to eat crappy airport food! It doesn't have to be anything expensive--some of my favorite places in NY are the cheapest. You could make a whole culinary adventure out of it: take the train in, get a fantastic dinner in Chinatown, then head to Little Italy for a cannoli and espresso. Or you could find a classic NY deli and get a nice pastrami on rye. Or anything else, from tacos to Tibetan. The possibilities are endless! And I guarantee it will be more memorable than sitting around JFK in the dark.
If you have any particular interests (food, sightseeing, etc.) let me know and I'd be happy to make some suggestions. Although I have a feeling this thread may get moved to the Non-Aviation forum...
[Edited 2004-11-21 04:31:26]
Common sense is not so common. -Voltaire