OAuth WRAP (Web Resource Authorization Protocol)
For a variety of situations where a developer simply wants to integrate with an API via POST the OAuth dance can a bit of a headache. OAuth WRAP is not much different than OAuth except that a client only has to pass the Access Token in the HTTP Authorization header, so it completely eliminates the need for signatures. All server-to-server WRAP calls happen via SSL. An additional benefit of eliminating signatures is that one can curl OAuth-WRAP requests without requiring any special libraries. There is an active working group fleshing out a spec and I expect to see widespread adoption of this in 2010 coming via products from the major service providers (specifically Facebook, Google, Microsoft, and Yahoo!).