I was wondering how hard it would be to enable a 'hiding' option that let me hide certain questions that I don't want to see. That way if it was a very active question that I have no interest in, I could simply click hide and not see it anymore.
The only foreseeable reason why this couldn't be implemented completely with a Greasemonkey script is that it would be nice to get replacement posts. As of right now, even the hide tag feature simply hides the questions after they were loaded. If I hid a lot of tags, I would end up getting very few questions on the home page.
This is, of course, due to caching.
