Amazon. Whether or not to make it available for Kindle is still under consideration. I don't know how useful it would be and whether it would really be worth my time. The first time I see someone with a tablet in use in a lab, I may go to the effort to make this available in digital format, but I still haven't seen it happen. Its coming, especially with the iORBI thing.
Big shoutouts got to David Berryhill at Johns Hopkins for critically reviewing this text and to Michael Mullendore for assistance with the sections on protein validation.