Pixelmator is a popular commercial image editing software for Mac OS X users.
Professional online broker and trading community.
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.
OpenCart is popular, powerful, and easy to use shopping cart software. Their healthy community forums are powered by phpBB.
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.