KDE is mainly known for producing the KDE Desktop Environment (used in Kubuntu) for Linux.
Conquer Club is an online multiplayer world domination game. The discussion forum is host to over 500,000 members and 2.8 million posts.
Active community for UK based Audi TT owners. Almost 30k members and 2 million posts, complete with unique style & powered by phpBB.
Developed by Focus Home Interactive, Cities XL 2011 is a city simulation game. Their community forums are powered by phpBB.
Gentoo Linux is an open source operating system built on top of the Linux kernel and based on the Portage package management system.
Meristation Magazine is a Spanish-language website featuring articles on gaming. Their discussion forums hold over 34 million posts and are powered by phpBB.