What if you could trade your expensive 5-pound Physics book for a cheaper, weightless e-textbook, downloadable to your iPod, iPhone or iPad? CourseSmart, a provider of subscription e-textbooks for college students, is making its 7,000-plus titles accessible on Apple Inc.'s iPhone, iPad and iPod Touch. The new applications, free for subscribers to CourseSmart, let students access their full electronic textbooks, read their digital notes and search for specific words and phrases. Some consumer reviews note that with the current e-book application, pages are hard to read, and the zoom functionality needs improvement. Still, caveats and all, the application may outweigh the hassle of lugging your books around campus!