I hope this doesn't get lost in the sea of ideas being put forth, but perhaps a simple solution is that a reader could mouseover an icon which would show the word count, number of external links, tags, and perhaps the number of images in a post and determine from that whether the post might have the qualities they are looking for. This leaves a lot of the decision making process in the hands of the reader, who probably has some idea of what structure he is looking for. A long article would have a high word count. If they are looking for pictures, the number of images might be relevant. If they are looking for links, then low word count and one link might be the perfect post for that moment.
I guess to summarize, if the fundamental building blocks of a post could be quantified (word count, link count, image count, tags) and displayed for the reader (mouseover display), it may make it easier for people to choose content without having to click through the link first.