How this isn't tmi.. After only peeking in out of sheer curiosity reading this has really given me some food for thought!
My other half was the first man I've ever had sex with when on my period, and I must admit the first few times I was a bit unsure. Mainly because my past partners (including kinky ones) thought it was gross, unsanitary, and one even told me that it was unnatural.. So my general perception was that it was an off-limits activity for the most part.
When I finally did get the chance I was amazed at how intense my orgasms were, though I think I mainly got off on the mess factor of it all. Makes me want to ask him if I could tie him up and make a bloody mess all over him.