We use MediaWiki for our wiki, and it provides some statistics out-of-the-box:

http://opensourceecology.org/wiki/Special:Statistics

Our forum also provides some statistics. In the list of discussions, you can see how many people are following a discussion, how many comments were made to that discussion, and how many people have viewed the discussion:
http://forum.opensourceecology.org/discussions

There's also a dashboard (visible to forum admins only):


However, I think there's no option to make it visible.

We also use Google Analytics (I'll have to check how to publish the stats).

I'll see if there's a way of embedding this information on a wiki page.