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.
Pixelmator is a popular commercial image editing software for Mac OS X users.
The Raspberry Pi is a cheap, credit-card sized computer. The official website uses phpBB for their discussion forums.
VirtualBox, developed by Oracle, is cross-platform x86 virtualisation software. It has become one of the most widely used virtualisation solutions in the world.
As the official board for the world-famous band Queen, this community hosts a wide variety of discussions by Queen fans from around the globe.
Official Support Forum for Debian, the kernel-based open source operating system. phpBB provides a solid platform for support and discussion.