This offer to join Frontier airlines frequent flyer program shall earn yourself 500 Free frequent flyer airmiles for joing their frequent flyer program
http://www.frontierairlines.com/travel/early_returns.asp


For those whom already belong to points.com and have a pointsplus account for which provides free exchanges calculated at not great exchange rates, you can grab the free 500 Frontier airmiles, and then immediately insert that Frontier ff acct number, to transfer those 500 miles to another frequent flyer account instead.

Keep in mind, if you do not already have an account at points.com await a later date for some special promotion to consider joining for making exchanges, as their transaction fees are truly like pulling your teeth, without drugs.

Worse scenario, grab the free 500 miles, and when that next freebie to obtain a free membership appears, shall advise you when to join points.com and if wishing, you may transfer those free miles into a different frequent flyer program.
Last note, make sure that you write down your Midwest frequent flyer account number and password after having joined,so you have access of that number if needed before your frequent flyer card were to arrive in the mail.