I just wanted to pass along a great site that allows you to search and download books in pdf form for free. Now before I post this I want to make it clear that I think we should still try to support authors as much as we can and still buy physical copies of books. I know that I prefer to read an actual book than to stare at my screen. Having said that, when traveling it is nice to save some room in your bag and just have a pdf version of a book.
Here is the link and hopefully everyone finds it useful: lib.freescienceengineering.org