There's one that's maintained by OzzModz, but was created by au lait:
With STUTC2 you can see how many threads a user has created. You can also see the TOP users and much more. Thread counter real time as well as the postings Notable Members Page "Most Threads" support for user ladder title support for trophy...
xenforo.com
I used this in the past and it worked very similar, but I'll stick with Lawrence's solution for now..