Gentoo Linux is an open source operating system built on top of the Linux kernel and based on the Portage package management system.
Official Support Forum for Debian, the kernel-based open source operating system. phpBB provides a solid platform for support and discussion.
Pixelmator is a popular commercial image editing software for Mac OS X users.
Fujitsu is a hardware and IT services company focused on providing IT-driven business solutions. Their community forum is powered by phpBB.
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.
The Raspberry Pi is a cheap, credit-card sized computer. The official website uses phpBB for their discussion forums.