Design Rules, Volume 1: The Power of Modularity, Carliss Y. Baldwin and Kim B. Clark. MIT Press, 2000.
Modularity creates value both at the level of systems and at the level of organizations. Baldwin and Clark describe a number of operators that affect modularity: splitting, substitution, augmentation, excluding, inverting, and porting. These operators have economic consequences on the systems they modify. This is a book that I will study again. (Reviewed Sept., ’05)