It's not ready for primetime yet, but I'm looking toward Sqrl for the near future.

It's totally open protocol that can be implemented with open source libraries, well documented, has an open-source reference implementation, uses well-known and tested crypto vetted by security experts, stores no secrets on the server that can be compromised, can work alongside existing login systems, and is the only password replacement system I know of that does not rely on a 3rd party.

The protocol was recently finalized so I'm hoping it will get some action in the WordPress community before too long.