elitefitness.com, hush.com.
You should have one for each account since they are only secure from elite to elite, hush to hush, ziplip to ziplip, etc...
All these listed above use the same Hush encryption engine and therefore are secure when sending to one another.
Ziplip is secure in a way to all e-mail addys because when you set the e-mail to secure the user has to click the password button which brings up a secure Ziplip session to read and reply to the original message.
Another advantage to Ziplip is this, and I think a lot of people overlook this feature: When you send send a message "secure" from Ziplip to any other e-mail including Ziplip you have the right to "revoke" that message at any time.
Now what use would that be? Here's an example. Let's say you order gear from a source and send him your address. You later find out that he gets busted. Well, you can immediately delete all of your sent messages thus removing any access that anyone (read: feds) has to these messages. Or you could just delete your sent mail after you recieve your package thus reducing the chance of your source storing any of your personal info.