I finally just bit the bullet and went to Toys R Us and looked for tin cases for my ebook reader.
Here is what I came up with!
I lined the inside of the case with craft foam. It's about 10 inches long, 2 or so deep and just an inch or two wider than the reader.
It definitely adds bulk to the reader, but now I think it will be safe bouncing around in a backpack for months at a time, and it will be at least pseudo water proof.
Connie