What other popular or high-profile web applications support two-factor authentication? I'd like to know which services I should turn on two-factor authentication for, since (at least for the two listed), it isn't the default.
- Amazon Web Services (AWS) supports two-factor authentication in the form of an RSA Token or using Google Authenticator
- LastPass also offers two-factor login using Google Authenticator
- PayPal offers two-factor SMS authentication