Some of these may be subscriber or member based. If there are any others I’ve missed, please post or email me (email@example.com).
Media magazine, publication of the Canadian Association of Journalists: caj.ca/mediamag/index.html
Ryerson Review of Journalism (Ryerson School of Journalism, Toronto): rrj.ca
Mediacaster Magazine: mediacastermagazine.com
Columbia Journalism Review (Columbia University, New York): cjr.org
American Journalism Review (University of Maryland): ajr.org
Editor and Publisher: editorandpublisher.com
These will discuss all aspects of communications, including media. While subscriber based, they have on-line archives.
Canadian Journal of Communications: academic studies of media and communications in Canada:http://www.cjc-online.ca
Public Relations Review: the oldest such journal in North America.
Public Relations Society of America (PRSA) offers three publications: Public Relations Tactics is a monthly newsletter of the latest news, The Public Relations Strategist provides information of value to communications executives, and Public Relations Journal provides a more scholarly look at trends in media and communications.