A couple of days ago I found out about Google Scholar which enables searching of scholarly publications. What would make this even more useful is if they combined it with a more comprehensive citation index.
Thinking about citation indices got me wondering, though: what if citation indices were annotated with the relationship between the newer publication and what it was citing? You could have relationships like "quotes", "summarises", "provides further evidence for", "argues against", "answers question posed by", and so on.
The granularity of many articles might not be right for this to really work given that one might argue for one part of an article and argue against another.
But it's theoretically appealing from the point of view of the richer searches you could do.
Continuing to think aloud: I wonder if it might be more practical in blogs. People could link to this entry with annotations like "agree", "agree with additional ideas", "agree with caveats", "seen something like this already", "really dumb idea with reasons stated".
Kind of an XFN for memes.