We have recently launched a search engine that helps users find niche
interest social networks and helps social network owners promote them.

Users search for sites related to whatever their interest is and
webmasters submit their sites tagged with related keywords.

The idea is that due to the increasing popularity and proliferation
of niche subject social networking sites thanks to Ning et al, users
have a way of finding like-minded communities and these social
networks receive targeted traffic that helps build user base and
monetize.

Please take a look! We are still building the database. Feel free to
register and submit your niche social network or social media site for
free.

http://findasocialnetwork.com