Bitcoins the hard way: Using the raw Bitcoin protocol

All the recent media attention on Bitcoin inspired me to learn how Bitcoin really works, right down to the bytes flowing through the network. Normal people use software that hides what is really going on, but I wanted to get a hands-on understanding of the Bitcoin protocol. My goal was to use the Bitcoin system directly: create a Bitcoin transaction manually, feed it into the system as hex data, and see how it gets processed. This turned out to be considerably harder than I expected, but I learned a lot in the process and hopefully you will find it interesting...