Something I'd like to be able to do is to track the citation history backwards from a given paper. But I want a couple of things that it looks like typical bibliographic sources don't do. As matters of computer or library science, I don't think they're terribly difficult. I've seen things done which strike me as much more complex.
Let's start with some paper, call it paper A. It cites, say, 15 papers (papers B, second generation). Each of those cites another, say 15, which at least temporarily means a list of 225 papers (C, third generation). Easy to get the list of papers cited by paper A (the 15 papers B1..B15), but significant manual effort, it seems, to get the collected list of papers C1..C225. One thing I would like, however, and which seems completely unsupported, is that I'd like a count of how many times each paper shows up in this tree. Some of the papers in the second generation probably cite others in the second generation. And it's near certainty that many of the third generation papers are cited by several of the second, and probably a good number of third generation cite each other. This is pretty much just a simple social network kind of analysis -- some papers have lots of friends, and some not so much. I'd like to see which papers are highly connected, and which aren't, working within the group established by papers cited by a paper of my interest (actually won't be one of my own in practice) and lines of reference descent from there.
The second sort of thing I'd like to see is for the chart to be continued through enough generations that sources like Newton's Principia start appearing on the list. I'm curious how many generations, in terms of citation history, modern work is removed from some of the landmark sources. Unfortunately, it seems that the bibliographic databases I have access to die out in the mid 1980s, which is a long time from when I want to be getting to.