Inspired by Jon Udell's link to a New York Times article on network maps of polarized political books, I wrote a similar program in C# and mapped the polarization between readers of "The C# Programming Language" by Hejlsberg et al. and "The Java Programming Language" by Arnold et al. It's really fun to watch when the network is just a couple of hundred nodes.
Unfortunately.... even with 2000 nodes, the books aren't connected! Amazing. I don't know what to do... maybe work outward from suspected "connectors" like "Design Patterns," and "Design Patterns in C#" and "Design Patterns in Java." Anyway, my SpringEmbedderPanel doesn't zoom out, so it's impossible to generate a readable universe of connected books in a single image. Here are two images, one from early in the run with the complete network in play(with "C# Programming Language" on the left and "Java Programming Language" on the right), and another showing a portion of the display when the network is only around 200 books.
It's a fun program; I can't release it yet because it's all in C# 2.0 (with typesafe generics for which I'm very grateful!).