In celebration of its 15th birthday on July 5th, Frontier Airlines is giving away 1,500 bonus miles to EarlyReturns members for qualifying Fall 2009 flights. Members of the airlines' frequent flyer program can earn the bonus miles for each roundtrip flight booked between July 1 and August 31, 2009 and flown between October 1 and December 15, 2009. Registration is not required. If you are not currently a Frontier EarlyReturns member, sign up and earn an additional 1,500 bonus miles. Click here for more info.