If you believe in karma, it should come as no surprise that e-readers are slowly killing off print books — perhaps in retaliation for all those trees murdered over the years. With the launch of Amazon’s Kindle Fire and Kindle Touch and Barnes & Noble’s Nook Tablet just days away, it’s cleear that e-readers are becoming must-have devices. E-reader and tablets have seen massive growth in adoption in the past year. A recent Pew Internet Project report said e-reader adoption doubled in the U.S. from 6 percent in November 2010 to 12 percent in May 2011. With more variety of devices and better price points (especially the bottom-of-the-barrel $79 Amazon Kindle), more folks will buy these devices impulsively.