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
NetBox - NetBox is an open source web application designed to help manage and document computer networks. NetBox was developed specifically to address the needs of network and infrastructure engineers.
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.
Snipe-IT - Managing assets with a Google doc or a shared Excel spreadsheet is more common than you think.
Zendesk - Zendesk is a beautiful, lightweight help-desk solution.
Zabbix - Track, record, alert and visualize performance and availability of IT resources