Networks & Graph Theory
Scott Weingart, "Demystifying Networks," Part 1–9. Start here: http://www.scottbot.net/HIAL/?p=6279
This series of blog posts provides an extremely accessible and clear introduction to networks and graph theory. They are written by someone with a strong background in digital humanities. Start with the first post, and then check out the other 8 (or so posts) in the series here and here.