Forums

phpBB

A popular open source forum that works well, a simple user interface and an admin group, it's easy to configure.
phpBB Guru - the official Russian support for the phpBB forum phpbbguru.net
Russian forum site phpBB myphpbb.com.ru

SMF

Elegant. Effective. Powerful. Free. And it's all about him. SMF - a package of programs of the new generation, is full of functions and at the same time having minimal demand for resources.

bbPress

Forum from the authors of WordPress. It is easy to install and fit into the WordPress engine.