My pick for the two-weeks-left-till-Dark-Knight is one of my all-time favorite Batman stories ever told. Originally appearing in a five-part series in Legends of the Dark Knight (16-20, which I was finally able to hunt down for myself), Batman: Venom tells a story from Batman's pre-Robin days.
In the beginning, Batman is confronted with a scenario that he's simply not strong enough to deal with. In a sewer, a 700 pound boulder stands between him and a drowning child he must rescue. Try as he might, the boulder wins and the child dies. Angry with himself, he goes to personally inform the girls father of the grim news. The father doesn't seem to shaken up and offers Bruce a special concoction of designer drugs to help make him better so that the next time he's in that situation the child doesn't have to die.
He declines, but not for long. His sense of guilt is too much and he quickly becomes addicted to the pills and becomes a monster, turning into a dark version of The Bat we wouldn't see again until Jason Todd's death at the hands of the Joker bring him to the brink of insanity.
Soon he realizes this was all a ruse designed to make him an obedient soldier, the men behind the drugs use his addiction against him and inform him that there will be no more unless he kills Jim Gordon.
You can only imagine where things go from there.
This graphic novel is something that I would advise everyone to have in their collections. It's some of the very best batman ever written, the art is very solid, the writing well crafted and the colors above-average for the era. And above-all, the story truly shows you what Batman is made of. His physical limitations coupled with his keen detective skills make this one of the most interesting and human tales of the Bat ever written. And the Introduction by the author, Dennis O'Neil, is really a fantastic read for anyone interested in the process of writing.
Also, Batman gets to fight a shark.