Features

Edd’s Tavern utilizes WordPressMU, buddypress, and bbPress

The following is straight from the buddypress site:

The Features

Private Messaging

BuddyPress private messaging works like internal site email. Members can message people on their friends list as well as forward and reply to received messages.
Each member will have their own individual Inbox, Sentbox, and Drafts folder. They will be notified of new messages by a new message count as well as email notifications if enabled.
Sending of messages to multiple friends, as well as site wide messages by an administrator are also possible.

Friends

Members of a BuddyPress enabled installation can be connected together by one member adding another as a “friend” and then the other member accepting the friendship request.
Each member has a visible list of their friends on the site. Friends lists are browsable and members can click on each friend to see more information – or add them as their own friend. Profiles are not restricted as a whole.
The ability to search for members by and piece of profile information is also included in with the built in members directory.

Groups

Groups in BuddyPress are a gathering of members, wires posts and forum topics. In future versions members will be able to post any sort of content to groups including blog posts, images and links.
Any member can create a group in BuddyPress. They then become the group administrator giving them heightened privileges within that group.
Every group includes a place for group information, and the latest group news which can be kept up to date my group administrators. Groups also include a group forum (bbPress), and wire where group members can engage in discussions. These features can be selectively enabled by group creator.

The Wire

The wire is a place where friends and other members can come along and post messages to a specific piece of content within a BuddyPress installation.
The wire will work with any component within BuddyPress, custom or official. For example, within the official components explained on this page – profiles and groups use the wire component. This allows members to post on other members profiles or leave messages for other group members.
Third party components can also make use of the wire and reuse the component to enable comments on their own custom content.

Activity Streams

Activity streams aggregate all of your activity across a BuddyPress installation. All of your friends activity is also recorded so you can check what others are doing on the site.
Every component can make use of the activity stream component, which means any sort of activity can be recorded. Wire posts, blogs posts, new friendships and blog comments are among the most popular activities recorded.
Custom components can also hook into the activity streams, meaning any sort of data can be tracked and recorded.

Blog Tracking

Allowing multiple blogs and multiple users per blog is a key feature to WordPress MU. BuddyPress preserves this functionality.
The blogs component will aggregate all blogs, blog posts and comments for a member across the entire installation. This means other members can easily find all blogs that a member belongs to or owns, as well as their recent posts and comments.
The blogs component also adds an easy to use screen for creating new blogs built right into the theme.

Forums

The forums component allows groups to create and manage their own bbPress forum. Group members can post and reply to topics all from within the group’s page.
Forums are not specifically tied to groups, they are generic, just like the wire. Forums can be attached to any content within an installation. This means third party plugins
and new components can make use of the forums component in the future.