If you have an iPad 3 or 2 and use a Smart Cover you should look into protecting the back of your iPad with a shell. The Union shell from Devicewear is in my opinion the best back shell available for both the iPad 3 and 2. This back shell will not only protect your iPad from scratches but it also has a magnetic strip to hold your smart cover open when in use and in book mode.
One of the great things about this shell is that it only costs $19.95. For more information about this shell and to purchase it you can visit