Ironically, your very best network contacts are sitting there with you every day, in class, at lunch, even in the library. Your best network contacts are other students who are also in your major and seeking jobs in your field. If they are truly active in their job search, they will have access to additional first-line contacts that can greatly benefit you. The relationship should be one of give and take, so that you are also providing them with networking contact information.
Your competition can also be your greatest ally.
Be sure to ask who they are contacting and what kinds of results they are getting. Find out if there are any companies on their list that you have missed. There can often be a great synergy among students who have worked together for the past several years. They may be seeking another geographical area and are happy to pass on their leads in the areas in which you are interested. You may be seeking jobs in a particular industry and are happy to pass on leads in the other industries to them. Some students have even organized informal job search groups to provide networking support on campus. If there isn't a job networking group (either formal or informal) organized on your campus, put a bulletin board up on your wall, offer a beer to all those who stop in with "Hot Tips for Job Seekers," and watch your board fill up quickly. Your Job Search Central may indeed become Job Search Central for many others as well.