AshleyMadison.com, which caters to men and women who are already in relationships and are looking for something more, is the largest dating service of its kind. The Toronto-based company has made millions of dollars by helping people cheat on their spouses. Their tag line gets right to the point: "Life is short, have an affair."
Not surprisingly, they also have an affiliate program. It must be an incredible lucrative setup, because they pay at least $200 per signup!