We just launched our latest e-book, Hands-On Precalculus (for free!) through the iBookstore. It features a completely new learning interface aimed at recreating a 1-on-1 learning experience through our Virtual Tutor. Check out the demo at http://schoolyourself.org/ and give us feedback!<p>A little bit about us: We're School Yourself, an ed. tech startup focused on high-quality, affordable, and interactive learning. We have two e-books out via iBooks right now: Trigonometry and Hands-On Precalculus, and we're working on Hands-On Calculus, which is coming soon.