The move puts the Nook under the noses of even more potential buyers. It's now sold at major chains including Best Buy, Staples, and Wal-Mart. Adding 3000 Radio Shack retail stores in the U.S. allows Barnes & Noble to more aggressively compete against the Amazon Kindle, which is sold in many of the same storefronts, and has already been in Radio Shack stores since June.

Holiday Favorite

While e-reader sales overall actually took a dip in the second quarter of 2011, IDC expects big growth in shipments over the holiday season to reach a total for the year of 27 million units, up from earlier estimates of 16.2 million. If current trends hold, at least a fifth of those e-readers will be Nooks.

For Barnes & Noble, the Nook has been one of the few areas of growth for the company, with year-over-year sales up 140 percent.

The Nook Simple Touch reader competes with the original e-ink Kindle, but unlike the Kindle, offers a touchscreen and retails for $139. The Nook Color also competes with other color e-readers, but is also being used by many as an inexpensive , given its ability to run a growing number of apps, and built-in e-mail and Web access. The 7-inch multitouch e-reader retails for $249, half the price of an iPad.