Better approval system: admins can go into the admin interface and check an 'approved' box for all users who submit requests. Verify that usernames aren't colliding.
Make it clear that username/password are Mason NetID
Put registration behind the login wall
Clearly show approval status in admin view without having to click on a user
Don't die if we haven't defined PIWIK_{URL,SITE_ID} or can't contact the
piwik server