I am not suggesting a bag of tokens. I think I would like some segmentation (e.g. a banking token that I wouldn't necessarily carry with me everywhere). But that's a personal preference - the more tokens, the more security and reliability. A single token can be used to sign on to many services. That's a technology that exists today - e.g. the US military, which deployed tokens to just about all service members and civilian DOD personnel, certainly doesn't give people a bag of tokens for all the services they need to access. They use a single sign-on system. I don't know if someone has already deployed this for general users (like OpenID) - but it's certainly doable if someone thinks there is a market for it.