Dark energy: Mystery of the Millenium T. Padmanabhan http://arxiv.org/abs/astro-ph/0603114 This is an impressive paper, based on a talk and quite readable.
I just finished reading it. What a lot of good solid MEAT in that paper. Obviously based on decades of deep thought by himself and semingly everybody else, it really does give us a general NECESSARY framework for evaluating quantum gravity programs.
He's got his references nicely organized by topic, I noticed. I liked the way he synthesized holography, thermodynamics, and special viewpoints to get his "model that works". Very convincing. I was especially diverted by his choice of variables for the action: the metric, the Christoffel symbols, and the curvature tensor. Noting also that the curvature tensor, in this representstion, depends on the Christoffel symbols but not the metric. I wonder how many decades of pondering the common wisdom of GR it took to come up with that!
What I really like is his ability reach a broad audience. Modern theorists tend to target a very narrow audience possessing great expertise in the subject material. This is not necessarily a bad thing. It's an efficient way to publish new research. Unfortunately, it leaves most of the rest of us slack-jawed. Here are some of his other papers I like: http://www.arxiv.org/abs/astro-ph/0602280 Issues in the Philosophy of Cosmology http://www.arxiv.org/abs/astro-ph/0602117 Advanced Topics in Cosmology: A Pedagogical Introduction http://www.arxiv.org/abs/astro-ph/0510492 : Darker Side of the Universe http://www.arxiv.org/abs/gr-qc/0510015 A new perspective on Gravity and the dynamics of Spacetime http://www.arxiv.org/abs/gr-qc/0503107 Understanding Our Universe: Current Status and Open Issues