There are two main foes in consumers' ongoing struggle to preserve their online privacy: companies that collect data and track people's online behavior to sell them things, and law enforcement agencies that collect data and track people to investigate crimes.

The rules for monitoring modern electronic communications are ill-defined. For the government, a warrant isn't currently required after a certain period of time for older information -- e-mail, social networking profiles or cell-phone location data -- stored "in the cloud" on Web servers.

Congress will likely try to address some of these issues during Obama's second term by updating the antiquated Electronic Communications Privacy Act of 1986, which dictates what types of personal information the government can access.