The conferencing software that The WELL's online community has been using for years has a "forget" feature which was always incredibly handy. If you just weren't interested in a certain topic that some folks went off on a tangent on, you could just "forget" it, and it would stop showing up anywhere you looked. You could always "unforget" it later if you wanted, but 99.9% of the time you'd just "forget" and leave forgotten. Very handy.
I'm surprised VBulletin, or whatever the web forum software is here, doesn't have such an age-old, time-tested feature.