Official Support Forum for Debian, the kernel-based open source operating system. phpBB provides a solid platform for support and discussion.
Inspired by Max Berry's book, Jennifer Government, NationStates is one of the most popular online simulation games. The forum boasts over 5 million posts and 200,000 users.
Pixelmator is a popular commercial image editing software for Mac OS X users.
Discussion forum for the massively popular American animated sitcom. Powered by phpBB.
Active community for UK based Audi TT owners. Almost 30k members and 2 million posts, complete with unique style & powered by phpBB.
The Raspberry Pi is a cheap, credit-card sized computer. The official website uses phpBB for their discussion forums.