Zendesk - Zendesk is a beautiful, lightweight help-desk solution.
Google Open Source - All of Googles open source projects under a single umbrella
Freshdesk - Freshdesk is a cloud-based customer support software that lets you support customers through traditional channels like phone and email, social channels like Facebook and Twitter, and your own branded community
Code NASA - 253 NASA open source software projects
HelpScout - Help Scout is a simple, straightforward way to provide excellent support
Disney Open Source - Explore Disney's Open Source projects