I do like the idea of the PHP documentation style comments, high quality reviewed comments that add to the text.<p>Maybe the answer is open text books. Schools most of the time, especially in K-12 wouldn't think about writing there own text book, but the combined power of teachers all over the world could surely produce texts that are far better than what we have today and I think a lot of teachers would contribute if it was just some pages here and there on things they were passionate about and the school sponsored them.<p>Sure you could still do limited publishing runs of this resource for people who would rather have a physical copy but it would mainly live online.