Marathon on a whim and more race discounts?!?!

My first marathon was on March 17, 2013.  Since then, I ran two more marathons (one of them being part of the 48.6 mile Dopey Challenge). After completing my last marathon as part of the Dopey Challenge I've been kind of taking it "easy" and just running (mostly speed workouts) and focusing on strength training, yoga, and mixing more cycling into my routine.  It's been going great, but every day I have this nagging in the back of my mind telling me that I need to do a fourth marathon before March 17th.