WordPress.com is brought to you by some of the same folks who work on the open source blogging software available at WordPress.org.
phpBB is a free flat-forum bulletin board software solution that can be used to stay in touch with a group of people or can power your entire website. With an extensive database of user-created modifications and styles database containing hundreds of style and image packages to customise your board, you can create a very unique forum in minutes.
OProfile is a system-wide profiler for Linux systems, capable of profiling all running code at low overhead.