An economic analysis of the Somali Pirate business model (wired)
Harvard Business Review this ain't.

Like any business, Somali piracy can be explained in purely economic terms. It flourishes by exploiting the incentives that drive international maritime trade. The other parties involved — shippers, insurers, private security contractors, and numerous national navies — stand to gain more (or at least lose less) by tolerating it than by putting up a serious fight. As for the pirates, their escalating demands are a method of price discovery, a way of gauging how much the market will bear.