SocialEngine - Socialengine PHP: Elevating Your Online Community Experience.
Task Coach - Task Coach is a simple open source todo manager to keep track of personal tasks and todo lists.
mooSocial - mooSocial is the best social network script to create a niche community or social site.
Todo.txt - Track your tasks and projects in a plain text file, todo.txt. A todo.
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.
Strikethru - Strikethru is a kind of to-do list notebook for managing work lists and staying updated with the important tasks.