If you have registered domains with RegisterFly.com and selected the free hosting option, make sure you change your default password for the hosting account.
EVERYONE with a RegisterFly.com domain, go to http://www.flyservers.com/build/lost.php and enter your email address that you have registered that domain with. You will then receive your username and password.
Login into your Flyservers account and change the password! I have notified Registerfly of this vulnerability.