Google bought the technology that would facilitate your volume slider. It was called PostRank: https://en.wikipedia.org/wiki/PostRank They even had a Chrome plugin for Google Reader that enabled just that on the client side.

I for instance, can't be bothered to read all of Hacker News. So I read only the posts that have 150 points or more, via http://hckrnews.com/ (a by-points curator) in the form of an RSS feed.