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.
mooSocial - mooSocial is the best social network script to create a niche community or social site.
EventMobi - EventMobi is an interactive mobile event app, audience response and engagement platform for conferences and trade shows.
JomSocial - Open Source Social Networking Software. Award winning open source community software by JomSocial. This social networking software is widely used by many Joomla users.