Most I/O psychology professors and graduate students belong to professional organizations. The Society of Industrial-Organizational Psychology (SIOP), the American Psychological Association (APA), and the Academy of Management (AOM) are some of the most common organizations I/O Psychologists join. Members of these organizations receive some publications, discounts on journals and books and business travel. As they say, "membership has its privileges," so get involved!
If you want to learn more about these professional organizations, click on the name.