Passpack allows you to use an existing login you have for your Yahoo! account as the login for your Passpack account.
How to Sign Up
To use your Facebook Login, go to https://www.passpack.com/online and click on the Yahoo! icon on the left, then use the Yahoo! Sign In button that will appear in the sign up dialog . This will take you to Yahoo! so you can login and give Passpack permission to access your account. You can then finish your Passpack registration by creating your Packing Key.
This short video shows how to signup for Passpack using a Google Account. The process for Yahoo! is similar.