For the threadstarter, when carrying your kindle around in your book bag, you might want to invest in something like this
http://cgi.ebay.co.uk/METAL-CASE-SON...3#ht_916wt_920
It's not elegant, but it works with most lightweight cases so you have double the protection. I have a bad habit of throwning my rucksack across the room after a long day at school so I got this for my Sony just for the piece of mind. I'm sure your kindle would fit in it too.