ToyOS is a project mainly written in ..., it's free.
Toy Operating System based on OSdev Wiki tutorials, textbooks and anything else I can get my hands on.
I must be crazy for doing down this path but this is the begining of a simple toy OS.
I've seen the linux source, read all the books, why not try it out for real?
Initially this is going to rely heavily on Bran's Kernel Development Tutorial at http://www.osdever.net/bkerndev/Docs/gettingstarted.htm
Also, IDT and VM code (and alot of other guidance to be honest) are based on the excellent turotial found here:
http://www.jamesmolloy.co.uk/tutorial_html/index.html