I enjoy all of Tanenbaum's textbooks, but their price here in the US is very high if you're just a hobbyist, or a professional for whom operating system design is a hobby interest, so you may want to get them from the library. (Or, for what it's worth, my personal copies are from India and were much cheaper.)
[1]: http://www.amazon.com/Distributed-Operating-Systems-Andrew-T...
It all comes down to Gustafson's Law [2].
[1] E.g., http://capinfo.e.ac.upc.edu/PDFs/dir25/file003041.pdf, http://www.mosix.org/pub/Process_Migration_for_OpenMPI.pdf, etc.
RAMCloud is a way to bring back Moore's law at this time:
https://ramcloud.stanford.edu/wiki/display/ramcloud/RAMCloud
That just struck me as a really nifty bit of trivia.
And of course C was developed for Unix.
What is it about operating systems and programming languages? :D
http://www.rgoarchitects.com/Files/fallacies.pdf
"This whitepaper is based on a series of blog posts that first appeared in Dr. Dobb's Portal http://www.ddj.com/dept/architect*