We recently picked up a Paypal security key to allow multi factor authentication on Paypal and Ebay. Wouldn't be nice if a security like this worked with all two factor autenication sites? Well, the closest thing is something called Openid which is an open source solution that provides a digital identity.
Now the great thing is that Verisign is now supporting Openid. If you go to http://pip.verisignlabs.com and sign up for a free account you can then use the account on any site that uses Openid (which is growing fast) but the really great thing is that is this Verisign service allows you to link the Paypal security key. This means when you use an Openid site you can can also use your Paypal security key to provide addition security via a one way password that is generated by the Paypal security key.