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.
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
Zendesk - Zendesk is a beautiful, lightweight help-desk solution.
Canny - Canny helps you collect and organize feature requests to better understand customer needs and prioritize your roadmap.
UserReport - Free online usability surveys with demographic information. Detailed click tracking for websites and feedback button for online user forum. Easy signup.
Nolt - A fast & beautiful way to collect user feedback