A field of power that is often missed is that of architecture. With it we mean physical barriers, like walls, gates, locks and fences, and especially their virtual counter-parts. In the software world DRM (Digital Rights Management; encrypting the data, and allowing it only to be opened by certain programs) is the equivalent to a lock. Lawrence Lessig called this Lex Informatica, as DRM often functions like a law.
DRM makes very strict control possible, down to how often one can play an iTunes song or whether one can print a PDF file. Architecture is determined by private companies and there are not many possibilities for other parties to influence it, apart from the buying-decisions of consumers, who already do not seem to like DRM implementations and their limitations. An other way around DRM are cracks and DRM-free copies produced by hackers. But this strategy has been made illegal in 1998 with the DMCA, which bans the breaking of DRM, even for exercising fair use rights. This means that DRM can not just act like a law, but even legally override law such as that granting fair-use.
On the other hand most of the current architecture is quite opposed to IP and DRM. This partially is so for the historic reason that the web was designed by academics, and thus according to the academic values of freedom and decentralization. Attempts are currently being made to change this by making the internet and computers less neutral with regard to the kind of data that is transferred, but because people copying things can also use encryption, these are not likely to be very effective without banning the use of encryption and intercepting all network-communication.