I found an organization whose mission is to raise awareness about media issues.

In their own words: "Mediascope is a national, nonprofit research and policy organization working to promote issues of social relevance within the entertainment industry. Founded in 1992, a principal objective is to encourage responsible portrayals in film, television, the Internet, video games, music and advertising."

One of the issues they deal with is Media Violence and Effects of Video Games. The web site http://www.mediascope.org/index.htm offers lots of journal and web resources.