Growl for Windows - Growl for Windows is a Windows-compatible version of https://alternativeto.
Communifire - Enterprise Social Collaboration Software
Notify OSD - Canonicals on-screen-display notification agent, implementing the freedesktop.
DigitalChalk - Online Training Software and Learning Management System (LMS)
Notifu - Notifu, a free open source pop-up balloon utility
Workplace by Facebook - Connect everyone in your company and turn ideas into action.