I made one kind of like Launie's, but with the elastic straps in all four corners of the right side of the interior. I will see if I can locate my old post, which I think has a link to the website I used for inspiration. I used my Kindle's measurements and added a little more padding than the original pattern.
There is also a cover out there for readers that allows you to stand your reader up on a table, which could be handy! I think I need to make one of those, too.