Info-Mac is a community dating back to 1984 as a mailing list and was the first online community for Apple's Macintosh computer. All of their content was converted to phpBB in 2007.
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.
Hugely popular Mozilla community providing support for Firefox, Thunderbird, Seamonkey and other well known Mozilla products. Over 350k members and 4 Million posts.
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.
The Raspberry Pi is a cheap, credit-card sized computer. The official website uses phpBB for their discussion forums.
Official Support Forum for Debian, the kernel-based open source operating system. phpBB provides a solid platform for support and discussion.