I just wanted to share a link to what I think is one of the easiest peices of software for the application-layer in the OSI model to setup and I mean, it's a fricken IRC server.
The configuration file uses the, correct me if I am wrong, YAML format and has comments included to make learning ngircd easier. I really love it - it's great.
Also I have created a test IRC network with it before and linked up some servers and I can tell you it works flawlessly (mostly, nothing is perfect).
Development is also active so that's great. Check it out!