KDE is mainly known for producing the KDE Desktop Environment (used in Kubuntu) for Linux.
It is the Italian Community for Ubuntu, a popular open source community operating system based upon the the Debian Linux Distribution.
Conquer Club is an online multiplayer world domination game. The discussion forum is host to over 500,000 members and 2.8 million posts.
Discussion board for the massively popular xkcd web comic. Covering everything from Maths and Science to Logic Puzzles and Forum Games. Over 100k members and 2.4 Million posts.
Support for Synology NAS devices and ideas for future versions of the DiskStation software.
OpenCart is popular, powerful, and easy to use shopping cart software. Their healthy community forums are powered by phpBB.