I am a mentor to a teen girl who lives in the housing project near my school. I can see her house from my window, yet, the housing projects are so closed off from the world, she had no idea a college was so nearby.
I also work at the YWCA (the 1st in the USA, I might add) with high schoolers helping them to understand how the media views them and using their own tools- NET, newsletter, audio and video journalism to create positive portrayals.
I also prepare meals at several local homeless shelters and a meals-on-wheels program for families whose primary breadwinner is living with AIDS.
Its not that tough to fit service into a schedule. If you have a lot of friends you can go as a group and do a major program (like Meals on Wheels) together two weekends a month. And by yourself, you can do tutoring or mentoring after classes.
Also, I am unaffiliated.