Gentoo Linux is an open source operating system built on top of the Linux kernel and based on the Portage package management system.
Fujitsu is a hardware and IT services company focused on providing IT-driven business solutions. Their community forum is powered by phpBB.
Conquer Club is an online multiplayer world domination game. The discussion forum is host to over 500,000 members and 2.8 million posts.
The VideoLAN project produces the extremely popular VLC media player software. Their forums provide support for users of the software as well as the development community.
Professional online broker and trading community.
Boasting almost 14 million posts, Ars Technica is one of the biggest and oldest technical forums still operating today. They use phpBB to power their forums and comment system.