I've been pondering a lot about this whole citation business. Does anyone here have ideas on how one would measure the quality of different citations? Objective answers only, of course.
In essence, you want to weigh citations higher that come from papers that are themselves "important" in some way. If you think of papers as nodes of graphs and citations as (directed) edges, then you are asking questions such as the "centrality" of a node in that graph.
In some sense, this is also related to the PageRank algorithm google uses/used to use: They also want to rank pages higher that don't just have lots of links to them, but links from other important pages.