Rockmelt actually does this. It's a browser built on top of Google Chrome. Along with a bunch of other features, it has one button in the top right where you ca

Rockmelt actually does this. It's a browser built on top of Google Chrome. Along with a bunch of other features, it has one button in the top right where you can take any page you're on and post it to Twitter, as a Facebook status, or on a friend's Facebook wall.