Shipud writes "The National Academies Press are offering all their books for free in PDF format. These are all the publications of the National Academy of Sciences, National Academy of Engineering, Institute of Medicine, and National Research Council. Lots of great stuff there, and now for free."
The most exciting phrase to hear in science, the one that heralds new
discoveries, is not "Eureka!" (I found it!) but "That's funny ..."
-- Isaac Asimov