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.
Official Support Forum for Debian, the kernel-based open source operating system. phpBB provides a solid platform for support and discussion.
Gentoo Linux is an open source operating system built on top of the Linux kernel and based on the Portage package management system.
Pixelmator is a popular commercial image editing software for Mac OS X users.
Solia Online is one of the most active online communities with over 18 million posts. Solia Online allows you to create your own avatar, buy items, and discuss topics with your friends.
OpenCart is popular, powerful, and easy to use shopping cart software. Their healthy community forums are powered by phpBB.