KDE is mainly known for producing the KDE Desktop Environment (used in Kubuntu) for Linux.
Joomla is one of the leading open-source Content Management Systems. With a userbase of over 400,000, they use phpBB as a reliable platform for support.
Discussion forum for the massively popular American animated sitcom. Powered by phpBB.
Zend Technologies is one of the largest and most popular companies producing a wide variety of tools and frameworks for PHP. Their community forums rely on phpBB.
Info-Mac is a community dating back to 1984 as a mailing list and was the first online community for Apple's Macintosh computer. All of their content was converted to phpBB in 2007.
Official Support Forum for Debian, the kernel-based open source operating system. phpBB provides a solid platform for support and discussion.