The Media of Mass Communication
This online textbook is frequently updated and is a wonderfully well-researched, objective and knowledgeable source of information.
 

The Media in Your Life
This is a concise, easy-to-use, frequently updated site that goes over all aspects of the media as it relates to society, and its duties and responsibilities in doing so.

Deja News
The greatest asset of this resource is the complete lack of objectivity. Many different authors share completely biased opinions in this news group to provide a multitude of viewpoints from which to choose on the issue.

The Internet Encyclopedia of Philosophy
Easily navigable and updated frequently, this site is quite comprehensive and in-depth.

Ethical Theories Page
Well-researched, concise, objective facts from an established philosophy professor provide a wealth of valuable information on the subject of ethics.

Official Federal Communication Commission Site
The FCC is an authority on the set-in-stone, legal aspects of media ethics; their site is very nice-looking and informative.

The Window
A well-researched collection of links and articles on philosophy. Very clean and simple to understand pages that make research tolerable.

American Communication Association
Not so much concerned with ethics as with mass communication in general, this is not the most useful or most frequently updated site in the world, but is presented nicely and easy to get around.

The Golden Rule
As a professor, Henry J. Gensler stays relatively objective in relation to a rather bias-prone topic. Site does not get frequent updating and is not terribly informative, but it is clean in appearance.

Hutchins Commission Site
This site is not dedicated in full to the Hutchins Commission in question on the media timeline (that of the 1940's); site is maintained well (but not very often) to provide a public outlet for a  group of professionals and experts. Not very in-depth or easily navigable.