So this isn't strictly necessary when using the Kindle, but it is DEFINITELY useful for using a laptop, which I assume most of us also have.
Amazon dropped the price on Belkin cushtops from $49 -> $10.99. I already own two of these and they're really useful.
Check it out
(link if interested) if you ever want to have kids
Edit: btw, the cheaper price is in the box at right (from Amazon, rather than a 3rd party).