Saying as you're trusting me with your password and such (as well as money, in some cases), it's very fair for you to want to know what I'm going to do with the information.
When you sign up, you provide me your email address and a password you want for your FTP and email accounts. Your email address (both the one you use to contact me and the one I give to you) will never be given out to third parties (explicitly for the purpose of advertising). Your password will stay safe, being put into a FileMaker database I'll be using to manage accounts (should something happen to your accounts and they need to be reset, I'd reset them to that password).
All files that you store in your directory can be seen by me. I will not give out the URL for any files on your site that are not readily accessable from your site (ie: if you have a file called "MyGirlfriendNaked.sit" on your site [first off, you're stupid], I won't send out the URL for that file, unless there is a link on your site to it).
If you have any other issues that you believe should be added to this policy, email me.