Exactly as Uxbod says

we all watch the forums and might occasionally go '"hey this RFE has had 4 forum threads created on it", but we have to amass the dozens of threads, tickets, comments, etc into one tracking software somehow!
Bugzilla allows us and you to:
-Track who's done what.
-See who's working on what.
-See how popular/who requested what from the community (votes).
-Note what paying customers requested it (tagged support tickets from paying customers get a higher priority obviously).
-Make suggestions on how to go about the actual implementation of a feature. (Or fix if it's a bug.)
-Get info when it's being worked on/finished (if your CC'd).
-Etc, etc.
PMweb then gives a nice sorted overview of the thousands of requests.
Bugzilla stores it & helps search for it, PM sorts it into predefined groups.