Lee,
I heard that quite a few times from other Kindle users. And have even seen it as a secret on some websites. It's not really much of a secret because it's actually in the manual that is preloaded on your Kindle when you purchased it. I actually didn't purchase a book right away after I received mine and spent time reading the owner's manual. Pretty much a first, reading the owner's manual.
Thanks Mark. I didn't know about the free.kindle.com addresses.
Lee