Open source support tracking in your browser
Kurisu OS 3.0
Simple, modern & fast web-based email client
TuxWordSmith uses XDXF dictionaries to play in 88 languages
Contao Open Source CMS (fka TYPOlight)
HTLS is an Hattrick live match viewer, based on the old Livefox.
The leading Open Source survey tool
Notepad++ project is moving to GitHub:
An OpenSource (C# .NET) TeamPlay Environment.