You can't transfer miles out of AirTran, but their flight coupons can be used on other airlines. A dozen AirTran flight credits will buy you an AirTran R/T. Two dozen will buy you a domestic R/T on any one of many other domestic airlines.

To echo another poster, it's not much of a leak, but you can get non-AirTran value out of AirTran's FF program.