A remarkable picture of the underdoped cuprates has emerged from recent quantum oscillation, high field transport, photoemission, and STM experiments. A central feature is the "nodal-anti-nodal dichotomy", the distinct behavior of the electronic excitations in different regions of the Brillouin zone. I begin with a spin density wave (SDW) metal, with electron and hole pockets, and present a theory of strong fluctuations in the local orientation of the SDW order. When the global SDW order vanishes, we obtain a novel quantum phase, the "algebraic charge liquid", which has Fermi pockets interacting strongly via an emergent collective gauge force. I discuss the pairing instabilities of these metals, using analogies to double layer quantum Hall systems. This theory leads naturally to a d-wave superconductor with very different pairing properties in the nodal and anti-nodal regions of the Brillouin zone.