Alberta Magazine Publishers Association
A site to build awareness and encourage the growth of Alberta magazines

American Jewish Press Association
Representing Jewish newspapers, magazines and journalists across America

American Society of Business Press Editors
A professional association for full-time and freelance editors and writers employed in the business, trade, and specialty press

American Society of Magazine Editors
A professional society for senior editors of consumer magazines

Association of Publishing Agencies
Representative body for Customer Magazine Publishers, formed in the UK, under the umbrella of the Periodical Publishers Association

Council of Literary Magazines and Presses
An organization supporting the efforts of the independent literary community

Fédération Européenne d'Editeurs de Periodiques
The European Magazine Publishers Federation represents the interests of  40,000 magazine titles

Finnish Periodical Publishers Association
Information in PDF format (in English as well as Finnish)about the magazine industry in Finland. The site also includes a PDF file with the organization's current membership directory

FIPP - International Federation of the Periodical Press
FIPP is a worldwide association of 34 national associations and more than 100 international publishing companies and associate members representing some 3,000 publishing companies

Japan Magazine Publishers Association
Information on the aims of the organization, ethical magazine publishing, and a profile of Japanese magazine publication, advertising, readership and distribution

Magazine Publishers of America Inc.
A New York based association of magazine publishers. These folks are on a very testy server, so you may find their site unavailable

Magazines Canada
Contains information for both publishers and readers of Canadian magazines

Nederlands Uitgeversverbond
The Dutch Publishers Association represents the collective interests of all affiliated publishing companies throughout the Netherlands: publishers of books, newspapers, magazines and of electronic media

Norwegian Specialised Press
Den Norske Fagpresses Forening - This site all in Norwegian

Periodical Publishers Association
TONS of information on this UK based site

Society of National Association Publications (SNAP)
A non-profit, professional society serving the needs of association publishers and communications professionals

Swedish Magazine Publishers Association
No English on this site, but with a bit of experimenting I found a membership list sorted alphabetically, as well as some neat links

Western Publications Association
Representing magazine publishers west of the Mississippi