Diaspora - The online social world where you are in control.
Eventbrite - Discover Great Events or Create Your Own & Sell Tickets
SocialEngine - Socialengine PHP: Elevating Your Online Community Experience.
Cvent - Cvent's event management software provides event planners with a complete solution to increase event attendance and decrease event costs.
phpFox - phpFox is a powerful social network platform for niche communities
Ticket Tailor - Ticket Tailor is an easy-to-use event ticketing platform that allows event organizers of all shapes and sizes to sell tickets online.