Telegram - Telegram is a messaging app with a focus on speed and security. It’s superfast, simple and free.
SocialEngine - Socialengine PHP: Elevating Your Online Community Experience.
Trello - Infinitely flexible. Incredibly easy to use. Great mobile apps. It's free. Trello keeps track of everything, from the big picture to the minute details.
mooSocial - mooSocial is the best social network script to create a niche community or social site.
Influitive - Influitive helps companies increase customer lifetime value and accelerate sales with the power of their own customer advocates. Inspire your customers to stay longer, share their experiences, and attract new business.
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.