I use the Kindle e-mail to receive ebooks or edocuments from:
Calibre
Baen Books/Webscriptions
Personal documents
Delivereads
It is super easy to use. Just remember to go to Manage Your Kindle and put in the information from the from website or e-mail you want to get documents or books from.
I have the Wifi Kindle 3. With the 3G+Wifi, I would only send to the
Youremail@free.kindle.com address.
Dean