SeatGuru.com: now you can fly comfortably even on the crappy budget airlines!
Some insider info on JetBlue's seating plans, for example:
"Seats 11 A,B,C,D,E,F are exit row seats and feature a good amount of extra legroom, maybe a tad more than row 12. During takeoff and landing, the seats are usually restricted from reclining, but once in-flight, the flight attendant will release a lever that allows for a full recline. Unfortunately, these seats are not available for preassignment and can only be selected on the day of the flight."