Orbitz.com
Priceline.com
Cheaptickets.com
Travelocity.com
there are bunches of them, BUT (and thats a big but), in order to save money you have to be willing to give a lot of sacrifices. Meaning, do not plan on flying during the weekend or "decent" hours of the day. the more comfortable you want your trip to be the more expensive it will be.
Latest Travel Deals Let You Save Big