Jetblue runs one direct flight out of JFK which is probably why you see so many New Yorkers. JBLU is constantly running deals. In fact, if you apply for the Jetblue card you get a free roundtrip flight...well it does cost $40 for the card. When you spend with the JBlue Amex, then it helps to build points for your next trip.

If you are in Baltimore, DC, Philadelphia, or Boston then you can take the Megabus or Boltbus up to NYC for about $15. Then go to Penn Station and take the LIRR to Jamaica Station. (15-20 minute ride from Penn to Jamaica) Then the airtrain into JFK. You can also AMTRAK it to NYC from the other cities, but I am going to take the $15 ride versus the $50 ride anyday of the week.

The Port Authority New York bus station is just 6 or so blocks away from Penn Station. If you are in a suburb, then you might be able to take Coach USA's shortline into the city which is on the 3rd floor.

In September, JBLU has a lot of deals.