I'm planning to write an operating system and I don't know very much about operating systems. Are there any good resources or books to read in order for me to learn? What are your recommendations?
We used Andrew Tannenbaum's Modern Operating Systems at the university I attended. I highly recommend it for it's clear explanations of the tradeoffs inherent in many of the design decisions that you'll run up against. This book is a little bit more "fair and balanced" than the Minix book.
I also recommend this book because, despite his net-famous flame war with Linus Torvalds, few of his biases come through in the book. Also, he's a pretty decent writer, and the book is actually entertaining.