If you do decide to rush/join, it can be a tremendous life experience, let alone a great asset to your application, especially if you take on a leadership role, as others have said. I was on the cabinet for my fraternity for 2 years, and also headed most of our community service projects. I'm proud of this and definately put it down on my AMCAS. I was asked about it during every interview, and I definately think it helped me. Being in a fraternity shows you can be social and hold other responsibilities while still holdin it down, grade-wise, in college. (Just don't party too much, as I barely got a 2.7 my first year...)
It's also a great networking tool, and I was lucky to have a couple guys a year or two older than me who were pre-meds, who helped me with all my classes and MCAT stuff... and if, by some chance, godforbid you (not YOU specifically, OP, but many people change their minds in college and even after college) don't actually want to become a doctor after another year or two of school ::gasp, did he just say that?:: fraternity networking will definately help you get a job.