I use my A5 Flex by Filofax as a portable writer's desk which houses my writer's notebook, my personal journal, and my Kindle eReader.
You can read more about my portable writer's Flex-desk in my previous post - How I use my Flex by Filofax
I like to keep my Kindle with my writer's notebook because I always forward articles from the web straight to my Kindle using a Kindle 'push' extension on my Chrome toolbar. I also email all of my edited manuscripts straight to my Kindle so that I can read through them as if they are eBooks, which is a much nicer experience than reading a word doc on my laptop.
It's so useful to have access to all of my research and written work while I am out and about, taking notes on buses and in coffee shops.
I would suggest always storing your Kindle eReader in one of the inside pockets of the Flex, to make sure it doesn't accidentally slip out and fall to the ground when you are carrying it about with you or taking it out of your bag.
If you are contemplating getting yourself an eReader I would definitely suggest getting a Kindle.
You can Browse Kindle Devices here, and find out which device suits your needs best. And instead of purchasing a Kindle cover, why not consider trying something a little more versatile, and so much cooler, like a Flex by Filofax!
Click on this link for a fun post on how I would like to improve the Flex by Filofax design