Nolt - A fast & beautiful way to collect user feedback

UseResponse - Open-source, self-hosted customer feedback software, live chat and helpdesk system that you can install on your server. Organize documentation using knowledge base and get feedback from social networks with centralized system

Product Pains - Giving users a louder voice to help teams build better products.

Canny - Canny helps you collect and organize feature requests to better understand customer needs and prioritize your roadmap.

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.

idea.informer - Idea Informer is a idea forum similar to uservoice or getsatisfaction.