As I have mentioned elsewhere, I find myself wishing I could clean up the forums a bit. In that vein...
1) Filters... I would love to be able to filter out threads. Just right click on it and say "filter." There are any number of topics that I have no interest in and while I *could* ignore them I think it would be helpful to allow me to clean up my view.
2) Auto Filter by keyword... If I could not see anymore threads on "Topic X" I would be a happy man. Keyword would, obviously, have to search the body of the Op as well as the thread title, but...
3) Optional Auto filter on "ignored"... Give the option to filter out threads created by someone on our ignore list.
4) Notify on keyword... Send us a PM if a thread comes up featuring a keyword. I could especially see this being useful in the marketplace forums.
None fo this is critical stuff, but I ove me my filters. Use them extensively in e-mail, and it makes it easier to find the the good stuff among the stuff which does not interest me. It also helps prevent my missing something that would be of interest because there is sooo much junk. (Junk, of course, being in the eye of the beholder.)