My kindle just got stolen as well. First thing i did was to deregister it from my account at http://amazon.com. that way you stop the thief from buying stuff. other than that get in touch with amazon support center from here:
(one thougth that came into my just now was that before i deregistered my device, maybe i should have had a document sent to it, explaining that the device had emotional value to me and please return to some someplace where i can pick it up. if the thief had any concious maybe he would do so... )
Yes. I just did it. You registered your kindle on the Amazon site just to turn it on. When you buy the warranty it asks you which devide you are adding it to. I'm a dropper, forget and walk into the ocean, etc. with my phones, so I bought it for my kindle.