Barnes & Nobles is offering MasterCard holders $20 off their Nook Simple Touch WiFi eBook Readers ($79) and the Nook Color ($149) with Free Shipping for a limited time.

The Nook Simple Touch Reader is 35% lighter and 6% thinner than the original nook. It features a high quality 6″ 800×600 touchscreen greyscale E-Ink display with 50% greater contrast, on-screen keyboard, WiFi 802.11n wireless (with FREE access at AT&T hotspots or in Barnes & Noble stores), 2GB internal memory, expandable with a microSD card slot, up to two months of reading time on a single charge, eBook library viewing, Nook Friends social networking, and access to many public library books for FREE.

The Nook Color features a stunning 7-inch color touchscreen, a sturdy build quality, magazines & newspapers in rich color, over 2 million titles at your fingertips, 8GB internal memory, built-in Wi-Fi wireless b/g/n LAN, and integrated browser for surfing the net, an App Store for extended functionality and all this built on top of the Google’s Android OS. The nook Simple Touch Reader is 35% lighter and 6% thinner than the original nook. It features a high quality 6″ 800×600 touchscreen greyscale E-Ink display with 50% greater contrast, on-screen keyboard, WiFi 802.11n wireless (with FREE access at AT&T hotspots or in Barnes & Noble stores), 2GB internal memory, expandable with a microSD card slot, up to two months of reading time on a single charge, eBook library viewing, Nook Friends social networking, and access to many public library books for FREE.