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.
VirtualBox, developed by Oracle, is cross-platform x86 virtualisation software. It has become one of the most widely used virtualisation solutions in the world.
Developed by Focus Home Interactive, Cities XL 2011 is a city simulation game. Their community forums are powered by phpBB.
GameServers is a premier Game Hosting company, having collaborations with big names such as Infinity Ward, Treyarch and Epic Studios.
The VideoLAN project produces the extremely popular VLC media player software. Their forums provide support for users of the software as well as the development community.
The Raspberry Pi is a cheap, credit-card sized computer. The official website uses phpBB for their discussion forums.