Survicate - Collect feedback on your website and find out more about your visitors.
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
Helprace - Helprace is a customer service software suite linking a ticket system with help desk software, giving customer support agents a complete helpdesk solution.
Zendesk - Zendesk is a beautiful, lightweight help-desk solution.
Noora - Building the features your users want is not an easy task. With Noora, you can validate your feature ideas and product roadmap before you start development.
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.