This site is devoted to discussing the intersection of software defaults and public policy. 
Defaults are pre-selected options chosen by the manufacturer or the software developer. Users tend to defer to these pre-selected options. Policymakers can take advantage of this deference by setting defaults in a welfare-promoting manner to enhance societal welfare. This has been argued by Sunstein and Thaler in the context of defaults for 401(k) plans under the concept of libertarian paternalism. 
I have written several articles on this topic, with Jay Kesan and Christian Sandvig.  This site allows me to continue this discussion and provide detailed examples.  Hopefully, this site will allow everyone to clearly understand the power of defaults and push developers to set them in a way that benefits society.
For background, see the following papers:
Shah, R. C., & Kesan, J. P. (accepted). Setting Online Policy With Software Defaults. Information, Communication and Society.
Shah, R.C., & Sandvig, C. (2008) Defaults as De Facto Regulation: The Case of Wireless Internet. Information, Communication and Society, 11(1), 25-46 (free draft version).
Kesan, J. P., & Shah, R.C. (2006). Setting Software Defaults: Perspectives from Law, Computer Science and Behavioral Economics. Notre Dame Law Review, 82(2), 583-634.