When I bought the T1 as a gift to my mom, I bought a Gecko case. It looks and feels great, while protects the reader awesomely.
I have just bought the T3 and the Gecko covers were a no brainer to me. It is well made, and well designed. It's a good quality product at a very reasonable price. So I bought theirs right away.
http://www.geckocovers.com/sony-prs-t3s-cover.html