To be honest, the site mainly targets straight users, but still, the LGBT community representatives are welcome to use the site. While registering, users get a chance to specify their gender and the gender of the person they want to meet. You can choose between these options:
a man looking for a woman
a woman looking for a woman
a man looking for a man
As you can see, AshleyMadison welcomes members of any gender and sexual orientation. The only problem is that the site is only free for females looking for men.