I have published a page on open textbooks (which is not to say “open books”); it is available in the blog sidebar and here.
My page is neither the best nor the worst such page you will see, but I do believe it is among the more convenient, dealing briefly with the what/where/why of open textbooks, including:
- What is an “open textbook”?
- Where to find open textbooks
- Problems with open textbooks
- Tools for remixing and re-authoring open textbooks
- Resources for learning more about open textbooks