Teacher-Developed Text Books

Great post over at edspresso on textbooks and the possible combination of teacher smarts and technology .  I've wondered about a wikipedia-style approach --wait! there is such a tool on the net.  Where have I seen it?  If I find it or someone sends it to me, I'll update this post.  Meanwhile, though I push reading, I suspect the poor writing, uninteresting approach, and shallowness of many texts help turn students off to real books, magazines, newspapers, etc.  For more on this topic, see Computer Science Teacher, and here.