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.
Support for Synology NAS devices and ideas for future versions of the DiskStation software.
Active community for UK based Audi TT owners. Almost 30k members and 2 million posts, complete with unique style & powered by phpBB.
Pixelmator is a popular commercial image editing software for Mac OS X users.
Gentoo Linux is an open source operating system built on top of the Linux kernel and based on the Portage package management system.
Discussion board for the massively popular xkcd web comic. Covering everything from Maths and Science to Logic Puzzles and Forum Games. Over 100k members and 2.4 Million posts.