I just made this little greasemonkey script for myself, so I thought I’d upload it for other people to use as well. Saves time spent counting threads manually. Of course, you probably won’t care how many threads are present in Denture Chat or Paranoid Panorama; I’ll let you add any exclusions for yourself. (Or modify the inclusions.)

How it works: Changes the header for the thread names, where it says “Title” to “Title (6 threads)” where 6 is the correct number.

Download at: http://userscripts.org/scripts/source/30939.user.js

Alternatively, if you would prefer a popup alert box as well, use the script at: http://userscripts.org/scripts/source/30920.user.js

Also, for the refresh/return version by Echuu: http://badbummonkey.org/gm/threadCounter.user.js