On a completely different take....
I have a
Clear mCoverŽ Polycarbonate Kindle Hard Shell Cover Case
I love this cover because I like to read my Kindle naked, and it has a stand on the back that allows you to stand it on your desk like a picture frame. The hard shell cover does seem to be pretty sturdy, and because it is clear it shows any decal you might put on your Kindle.
Also it exposes the keyboard, but I like to tape a clear plastic flap (like a piece of overhead transparency) over it like a trap door so it is accessible to use but still keeps the dirt out.