I set up Google 2-factor authentication for some of my accounts. Some useful pointers:

• Add another phone to the list Google will call: https://accounts.google.com/b/0/SmsAuthSettings#devices
• Assign a password for an app on a device: https://accounts.google.com/b/0/SmsAuthSettings#asps
• Show/edit computers that 2-factor authentication knows as yours: https://accounts.google.com/b/0/SmsAuthSettings#registered
• Print/display offline/backup 2-factor codes for when you don’t have phone service: https://accounts.google.com/b/0/SmsAuthSettings#registered