Adblock Plus is one of the most popular Firefox Add-ons in the world, with over 10 Million daily users and over 100k downloads a day. They use phpBB to offer support to their users.
KDE is mainly known for producing the KDE Desktop Environment (used in Kubuntu) for Linux.
Independent site for Dutch horse lovers. With over 280,000 members and 95 million posts, Bokt.nl is widely acclaimed as one of the largest boards powered by phpBB.
Joomla is one of the leading open-source Content Management Systems. With a userbase of over 400,000, they use phpBB as a reliable platform for support.
Support for Synology NAS devices and ideas for future versions of the DiskStation software.
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.