My period is a much better experience since I've become vegan - specifically, following the Dr. McDougall program (which is whole plant foods, starch based, no oil vegan).
My periods are at least a day (sometimes more) shorter than they used to be and the cramps are either very light (requiring no medicine) or not there at all (not noticeable). The flow is much more manageable (don't need those overnight pads during the day any more).
I read about this happening to other converted vegans in a booked called Prevent and Reverse Diabetes (title was something like that) by Dr. Neal Barnard. In the book he talks about a medical study that showed when women switched to a vegan diet their periods became lighter and cramps were either lighter or went away. He explained in there that the hormones in dairy and meat over-increase the buildup in the uterus from what the woman's body would naturally do without those extra hormones.
So there is that option, which I feel is a good one, since Dr. McDougall's program also prevents and reverses heart disease.
EDIT: I forgot to add that this is a very MMM attractive option since starches and veggies can be found much cheaper than meats, particularly if you bargain and bulk shop. (There are a lot of eat for $3 a day threads on the Dr. McDougall forum.)