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
Doorbell.io - Collect in-app user feedback. Available on websites, iOS, and Android.
Usersnap - Usersnap is a customer feedback software for SaaS companies that need to constantly improve and grow their products.
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.
Saber - Quick and Easy Website Feedback - Stop losing customers to website errors and usability problems. Get Saber's website feedback tool for quality user feedback, suggestions and bug reports.
Zendesk - Zendesk is a beautiful, lightweight help-desk solution.