Drinks: The only thing from Boston that anybody in New York will enjoy is the Sam Adams Bar in Terminal B. In Terminal C there's Slip Mahoney’s Irish Pub -- not quite what you’d see in Gangs of New York, but it’s also considerably safer.
(VERY) Last minute gifts: Shop for Jay Z (or your bro that likes snapback Expos hats) at Lids at the Center Food Court. Hit the MOMA store for the highest culture you’re ever gonna find in a food court, and a last-minute somthing for Mom.
Still bored?: There’re two Xpress Spas in Terminal C. Go relax.
Escape: If the Mets are in town, and you feel like rooting for them because no one else will (oh snap, another Met's joke), Citi Field is a very short cab ride to the other side of the tarmac. And, shockingly, good seats are pretty much always available. If the Mets are not in town (see: Holiday Season) and you have four hours or more, the Port Authority bus into Manhattan takes about 25-35 minutes.