I have installed a Buddypress installation for a client wanting to create a community blog. I also installed BBPress for community forum posts.
Buddypress extends WordPress so it can be used as a social networking site. It is like having your own Facebook-type website that hosts a family site or a community interest of some sort. You can set up group discussions and activities, and you can allow community blogging. With some expert help, you can seamlessly integrate BBPress to allow forum posts.