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

Yotpo - Yotpo is the smartest way to generate customer content, drive traffic and increase conversions.

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.

Viral Loops - Viral Loops is a viral and referral marketing platform to launch ranking competitions, sweepstakes, pre-launch and referral programs.

Zendesk - Zendesk is a beautiful, lightweight help-desk solution.

Swagbucks - Swagbucks is a loyalty program that offers individuals rewards for engaging in various activities. Users can earn reward points for performing Internet searches, purchasing items from affiliated vendors, or completing polls.