I am not kididng you - I have taken it 5 times.
The first three times, I took it while in school, getting evenly-distributed 27's and 28's. With my low GPA, that was not good enough to get into med school. I re-took it once again (studying while working full-time), and got a 26, and gave up on being a doctor.
Last year, I decided to give med school one more good shot...took a review course, and got a 34. My situation is somewhat different, because it's been 3 years since I last took it. So my score can be looked at either as a statistical anamoly or actual preparation and improvement. But I was at the point where I figured it couldn't hurt me to take it again, so I did.
After taking it 3 times, however, you have to give a good reason for taking it again - which means demonstrating that you plan to use these scores to apply for school. That simply involves sending them a copy of a rejection letter (we all have plenty of those lying around, right?) or completing your AMCAS application before you register for the MCAT, which is what I did.
I'm still hoping to get in off my M.D. waitlist (Wayne State), but I've got a D.O. acceptance, and am on a couple of other D.O. waitlists. I don't think anyone is looking at my re-takes unfavorably; for me, it's really just a question of my low GPA. However things work out for you, good luck, and I hope you don't have to take it as many times as I did!