The Feynman Lectures on Physics probably constitute the most famous introductory physics textbook ever written. The level of intuition it provides is hard to beat; I first started reading it in middle school, and a decade later I'm still finding new insights in it. Yet when I recommend it to others, they often have sticker-shock. It is a three-volume book, after all.
So is there any legal way to read the Feynman Lectures for free, on the Internet?