Attending job fairs is an excellent way to meet multiple employers at one location. Check out these two websites regarding upcoming job fairs in addition to tips on how to be successful at a fair. Note that many job fairs are restricted to students from participating schools.
Job Fair Tips
Dress professionally - Wear a suit, handle this as you would a regular interview.
Resumes - Bring a supply of resumes to hand out to the employers. Take a portfolio/briefcase to hold your documentation (e.g. resumes, writing samples,firm literature, etc.). And don't forget to bring a pen or two!
Prepare a "one minute commercial" - Think about your strong points, your goals, the employer and where you want to go within the organization. How do you 'fit'?
Be prepared - to discuss where you want to work geographically (New York - Boston - anywhere), what you like doing, what you're looking for in a job, what you most relevant skills are.
Arrive early - Plan on extra time for checking in.
Network - While you are waiting in line, talk to others. You may hear about opportunities of which you were unaware.
Be assertive and show initiative - shake hands and introduce yourself to recruiters when you reach the table.
Be enthusiastic - Employer surveys identify one of the most important personal attributes candidates can bring to a new position as enthusiasm. NALP, in fact, has reported 'lack of enthusiasm' as one of the top three reasons candidates aren't considered for positions. (Arrogance and poor communication skills are the other two.)
Stay calm - There will be many applicants approaching employers at the same time you are... Don't be overwhelmed by the experience. Keep a positive attitude and concentrate on the benefits of the experience.
Explore options - A wide variety of organizations will normally participate. This is an excellent opportunity to browse and indulge your curiosity.
(Adapted from http://jobsearch.about.com)