Using 2-step verification
Improve security of your Google Account using 2-step verification. Learn more: http://google.com/support/accounts/bin/static.py?page=guide.cs&guide=1056283&topic=1056284
Use 2-Step Verification without your phone
Do you use 2-Step Verification to sign in to your Google Account? Learn about backup options to receive codes so that you can sign in even when you might not have your phone around.