In the year or so since this site went up, we've received between the two of us almost a dozen requests of this kind. Every single one of them has been from men. Not a single woman has asked us to try and set her up with a gay man. On the other hand, almost every gay man who has made this request has claimed that such an arrangement would be great for the lucky lesbian involved, and told us that we would be doing our community a grave disservice by not passing on their request.
So I thought I'd share some of my thoughts on the matter (after discussing this with Kara).
Yes, there are lesbians who have chosen to marry men for the purpose of having children, and in some cases just to avoid problems with their community. In fact, there are probably more lesbians who have done this than there are gay men. However, if a lesbian chooses this route, the chances are next to nil that she will choose a gay man as her husband.
The concerns of men and women are different. The concerns of gay men and lesbians even more so. One major issue in this case involves "performance issues". These are a great deal more prevalent among men than among women, regardless of whether they are straight or gay. It may be that a gay man who feels the need to marry a woman would prefer a lesbian wife because he imagines that he won't need to worry so much about pleasing her. And that's understandable. But the same concern is unlikely to be shared by very many women.
A lesbian who decides to marry a man has two major options when it comes to sex. She can find a way to get enjoyment out of it, or she can "close her eyes and think of England," so to speak. If she chooses the former, she's probably better off with a straight husband, and if she chooses the latter, it doesn't really matter. Except that a straight husband is probably more likely to be attracted to her, which is something most women would be likely to prefer.
This is not to say that marriages between gay men and lesbians cannot work. I know of one or two cases, by hearsay. But I know of very many more cases of gay men and lesbians who are married to straight partners, some of whom know their spouse is gay and some of whom do not. Of these, the vast majority are lesbians with straight husbands, but I know of cases where it's the husband is gay, and his straight wife is okay with that.
If you are intent on trying to find a lesbian to marry, you might want to try http://www.nuyenta.com. I understand that they are a dating service of sorts for the GLBT Jewish community. This isn't an endorsement of their service, but you can try. Neither Kara nor I will pass on any requests from gay men who are looking for lesbians in this way, so please don't put us in the position of having to explain why each time.