vldPersonals - Full-featured PHP solution for running an online dating site.
BuddyPress - WordPress social networking in a box.
Skadate - Skadate is a dating software.
Elgg - Opensource social network engine
ProDatingScript - Start your own dating kingdom using ProDatingScript which includes Windows Software,Android App! Buy now to get the key to the kingdom
SocialEngine - Socialengine PHP: Elevating Your Online Community Experience.