They ask you to allow their e-mail address to send files directly to your Kindle -- so Amazon would be charging my credit card a small delivery charge each week. (Since I'm still using a Kindle 2!)
The site defaults to the free.kindle.com account, but you have to take it on trust that they will only use that one, and although they say "If you have an older kindle, select the regular @kindle.com address using the dropdown menu above." they don't explain the implications of that on your credit card.
