OzMan

There are many more than those three. Until a comprehensive list is made, the easiest way is to install Zango yourself on an old pc and type in an adult domain (your own sites especially) or keyword and see who pops up, who are on the toolbar and who is listed on the Zango search engine.

I was quite surprised who I found, especially the mainstream results for adult stuff. I did get an awesome 3D Earth screensaver though so I think I came out ahead!