Having only recently realized just what StackExchange is and how to use it (I'd been running across it in Google searches for a while), one frustration for me, in looking for questions to answer, is an inability to tick off questions I'm not interested in answering, which continue to clutter my view of the site.

At web scale, everything is crud to 5 nines. Give me noise controls. The good stuff's in there, but you need to be able to surface it.