This board doesn't tend to be a good place for finding partners, since the majority of people here already have partners, and we're scattered all across the globe.
I haven't spent time looking for a partner who practices domestic discipline, since by the time I realized that was what I need, I was already married to my wife. So I don't know of any sites, but I know some people have posted suggestions when someone joins the forum with that goal in mind.
So, if those of you who know of sites would be so kind as to list them here, we can keep a list handy for people who are looking for partners.
(That is to say: please post links to sites that are helpful for finding a partner who does some form of discipline. Thanks!)