aTalk - An encrypted instant messaging with video call and GPS features for android.
UserVoice - UserVoice integrates easy-to-use feedback, helpdesk, and knowledge base management tools in one platform that empowers users to speak and companies to understand.
Talk360 - Talk360 is a best-in-class communication utility that offers a convenient way to connect with loved ones globally.
Freshdesk - Freshdesk is a cloud-based customer support software that lets you support customers through traditional channels like phone and email, social channels like Facebook and Twitter, and your own branded community
FluffyChat - Open. Nonprofit. Cute ?
Zendesk - Zendesk is a beautiful, lightweight help-desk solution.