It's common that I read a question and say, "OK, I don't need to see it again."
Then I always think, "Hmm... maybe there is a 'hide' button on the question, so that I won't see it again in my favourite tag list so that I'll be able to focus on the remaining questions which are either new or known by me and interesting to me?" But, unfortunately, the button is never there.
Request: Let's implement that button! No need to clutter the database with it: It looks to me like a perfect candidate for HTML5 local storage. Purely client side.
The fun part is, it can be implemented separately from SO, as a bookmarklet or just an addon for PersonalizedWeb / GreaseMonkey. But I believe it would be indeed useful to have it there available for everyone.
Do you like the idea?