OK, this is a blatent post about a post - but Scoble does it, so why can't I!
I was reading this post by Josh Ledgard talking initially about the pop-up blocker that will be built into Internet Explorer that ships with XPSP2. Its certainly about time (although, they missed the boat, I use the Google toolbar - indispensible), however as Josh points out the whole area of pop-up blocking has been made more complex with the addition of Flash based ads which roam around a web-page like slimer off Ghostbusters.
To be honest my online experience revolves around Outlook, Google and a handful of technical sites and newsgroups which Google effectively indexes. So I don't see these free roaming ads too often, although when I do my aural senses tend to be assaulted. To solve the audio problem I propose that Windows (no later than Longhorn) has a set of controls next to the minimise, maximise and close button that allow you to control audio settings on a per process basis. This contextual information would be available as a per-process master switch to stop ANY audio coming out of certain processes.
Without looking too deeply into it, this doesn't seem like a hard problem to solve.