Then I found that San Francisco is the place to learn about sex! There is the Institute for the Advanced Study of Human Sexuality and they offer degrees and all! That's not actually forum worthy.
They do however publish a journal - Electronic Journal of Human Sexuality. Some of the articles there look interesting. The first one for example is "The Swinging Paradigm: An Evaluation of the Marital and Sexual Satisfaction of Swingers." These actually look like real scientific papers not just more personal essays and opinions.
I don't have time to browse this right now, but I thought some people might find it useful.