Reason TV put together this great video on the impact a patent An entity in the business of being infringed — by analogy to the mythological troll that exacted payments from the unwary. Cf. NPE, PAE, PME. See Reitzig and Henkel, Patent Trolls, the Sustainability of ‘Locking-in-to-Extort’ Strategies, and Implications for Innovating Firms. is having on one business in particular. It is worth a look.