The best-selling genre e-books are romances of all kinds! Light romances, medium romances and extra spicy romances like “Fifty Shades of Grey” by E. L. James which is currently the number one title on the New York Times Bestseller list. People seem to like romances in the e-format because they can be discreetly read on almost any Wi-Fi enabled device and can also be read almost anywhere, i.e. while standing in line at the grocery store, waiting in the car to pick the kids up from school, waiting for your significant other to finish shopping etc.
Here is a link to a New York Times article on the very popular E. L. James trilogy of books which are not yet available in the print book format; but, which are available as e-books from Barnes & Noble and Amazon:
Enjoy your weekend everyone!