I have just come across Motion Mountain, Christoph Schiller's online physics text book and am deeply impressed. Think of the Feynman Lectures in Physics re-done by a Donald Knuth and then released as a free PDF file. To quote John Baez:
It's an enormous feast of ideas - romantic, wildly ambitious, and still not finished at 1459 pages. Using a bare minimum of math, it conveys an enormous amount of physics, all focused on the question "what is motion?" This question is very deep. We have made tremendous progress towards answering it, but are nowhere near done.
I have put a copy on my laptop and will be probably spending much of 2008 working my way through it on the train to and from work. I do hope it eventually comes out as a proper book.