SJU offers over 100 different clubs and organizations. These vary among service organizations, athletics (varsity, club, and intramural), performance organization, special interest groups (such as the Asian Student Association and student government), along with Greek life (about 12% of students participate).
SJU also offers free and cheap activities on campus and through out the city on the weekends. We are only about two stops on the R5 (Overbrook Station) train into center city, so it's easy to find something to do if you are looking to venture off campus.
For more information on student activities, please check out their web page. SJU: Student Life - Student Leadership & Activities - Student Organizations
Hope this helps!