The rec.arts.tv FAQ:

Last updated:  February 29, 2004.
This version:  8.00

Here are some of the main TV-related organizations (Government & private) the exist:

The Emmys (A.T.A.S.): www.emmys.org	The U.S.'s Academy of Televisions Arts and Sciences (ATAS) web site, devoted to television's Emmy Awards, among other things.
Federal Communications Commision (FCC): www.fcc.gov	The web site for the Federal Communications Commision (FCC), which establishes standards for TV (and radio); (important) recent FCC rulings can be found here.
A.C. Nielsen Company: www.nielsenmedia.com	The web site for the A.C. Nielsen Company, the people enigmatic TV ratings system; this site is now expanded to include an explanation of how the aforementioned Nielsen ratings work.
Museum of Broadcast Communications: www.museum.tv	The web site for the Museum of Broadcast Communications, it contains an extensive archive of TV (and radio) related information.