I tried using the Return only threads with no replies feature with everything else blank. My hope was to dredge up all threads with no replies. I figure there are probably some questions which get asked and never answered, and I was going to try and remedy that. Some might get discouraged and wander off if they ask and never hear back.
Feature doesn't appear to work. All the threads returned seem to have replies on them. Perhaps threads aren't being properly flagged with no replies.
In fact, ability to search for threads with greater than or less then a given number of replies would be helpful. Find the threads with a lot of responses or the ones where it's quiet and there might be some unanswered questions still.