private messages

I eventually want to hunt for someone to do development on this idea, but first I'd like to find out how it can be designed to be of greatest benefit to the community.

I want to be able to manage access to a node, with CCK fields. The node should be viewable by both a role and at least a single (ideally multiple) user(s) not in the role.

I installed phpbb3 and phpbb module.

"Forum stuff" block shows 3 links: private messages, unread topics, unread posts. Links to topics and posts work, but "private messages" links to a "forum/inbox" which doesn't exist. But inbox exists, I can use it from the forum.

Why?

While Drupal specializes in simplicity, competing with forum software like phpBB or Invision requires more depth in terms of individual pieces. One of the most underdeveloped modules is, without a doubt, the private messaging module. Compared to other types of PMing, this module can certainly be expanded. What do you think could make PM-ing more interesting for users on a site?

My ideas:

Folders: Letting users create folders for their PMs would certainly add a needed feature. On some sites (no Drupal ones I use, but certainly on forums), I receive a ton of messages, so letting me sort them is certainly a convenience.