SocialEngine - Socialengine PHP: Elevating Your Online Community Experience.
Communifire - Enterprise Social Collaboration Software
mooSocial - mooSocial is the best social network script to create a niche community or social site.
DigitalChalk - Online Training Software and Learning Management System (LMS)
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.
Workplace by Facebook - Connect everyone in your company and turn ideas into action.