I would add:
* Vanishing Voices: the extinction of the world's languages by Daniel Nettle & Suzanne Romaine
* Language in Society: An introduction to Sociolinguistics by Suzanne Romaine
Well, of course, these books are more related with Sociolinguistics and its stuffs but they are fundamental for all teachers, no matter what specific subject they teach. Why? Because 90% of today's languages could be extinct by 2100 and language diversity may be as important as bio-diversty. Long-stablished cultures hold precious insights into the world. Letting them die may lose us invaliable knowledge in many fields.
I would definitely recommend The Power of Our Words in the Responsive Classroom series. Too often we don't think about how the words we choose in the classroom work against us.
I also loved Teacher Man by Frank McCourt as an inspirational and nitty-gritty, real-life story.
If you are looking for a great network that revolves around books, Goodreads is a great place to start. You can make bookshelves, share your shelves with friends, create book clubs and discussions and also write reviews.