GamesForum.ca is a video game community.
egosoft.com is the community of game developer EGOSOFT.
My eHangout is a general chat community.
woot! forum is the community of the woot.com online store. woot.com is "run by the employees of a 10 year old consumer electronics distributor that focuses on close outs and generally buying stuff cheap." They sell 1 item a day and use phpBB to allow people to discuss the products that they sell.
XPForum is a help and support site for users of Microsoft Windows XP.
The DEVPPL FORUM is a web development and technology discussion community.
Mike Lothar is home to template author Mike Lothar (shock!) and it features a very nice, clean, crisp, professional look with some nice subtle accents and touches.
WritingForums.com is a discussion community for writers that features a nice, clean and professional phpBB template, including some nicely integrated hacks.
This nicely integrated phpBB serves as the support community for Nucleus CMS, a popular GPLed blogging software.