I love this idea. I always, take a famous open source project and try to re-create or go through the source of it. Its very tough, but when you do so the learning is very immense. Thanks for the link.
Late comment but a good way to do this when you're digging through the source and look at the early commits to see where it started. I remember going through Linux 0.0.1 to boil down the essentials of the kernel for example.