What source code is worth studying?
jsyedidia: I highly recommend the Stanford GraphBase, written by Donald Knuth. It's C code written by Knuth using the literate programming tool CWEB. If you don't know about CWEB, it's not hard to learn how to use, and probably is already installed on your system if you have TeX. The Stanford GraphBase is available for free download on Knuth's web-site, and also comes bound in a nice paperback book, that was reprinted in 2009. Knuth also makes available many other programs written using CWEB on his web-site, but I would start with the GraphBase.