Noah Smith has a great post on how the Economics Job Market works in the US. Since this Market includes faculty positions, this part came as a surprise -- and I'm sure it would cause deep envy among those who can't hope to even apply for faculty jobs before 3-6 years of post doc experience):
What do you need in order to go on the Job Market?
You need a Job Market Paper, or "JMP." This is a piece of original research, usually the first chapter of your dissertation.
That's it! Really! That's all you need! In the words of the great professor Yusufcan Masatlioglu, "All you need is that one damn paper."
At your AEA Meeting interviews, you will mainly discuss your JMP. At your flyout, you will present this paper. You don't need to have published this paper; in fact, you don't need a single academic publication (most people save publishable papers for when they are already working as assistant profs, where the papers will count towards tenure). "All you need is that one damn paper."