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.
Zendesk - Zendesk is a beautiful, lightweight help-desk solution.
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
UserReport - Free online usability surveys with demographic information. Detailed click tracking for websites and feedback button for online user forum. Easy signup.
Canny - Canny helps you collect and organize feature requests to better understand customer needs and prioritize your roadmap.
UserEcho - UserEcho gives you the opportunity to create a modern Community to support customers in a few minutes. It includes support forum with the possibility of voting for ideas, Helpdesk, Knowledge Base and Online Chat.