Rapid Prototyping with JS is a hands-on book which introduces you to rapid software prototyping using the latest cutting-edge web and mobile technologies including NodeJS, MongoDB, BackboneJS, Twitter Bootstrap, LESS, jQuery, Parse.com, Heroku and others.
I downloaded this and the PDF looks nice. I'll try the EPUB file on my Nook later. I'll read it and if I like it, I will likely go back and purchase it for real. Thankyou leanpub for making this available for free.