A big part of the problem is concentration of media ownership.
For example, NewsCorp, the company that owns Fox Networks and 20th Century Fox, also owns Sky Satellite TV, MySpace, HarperCollins, more than 175 newspapers and many other media. All under the control of one man, Rupert Murdoch.
There should be more regulation of media market share, to ensure that no one individual or company can influence the opinions of so many people.
Check out this neat chart of the major media alliances:
Media ownerships