It may be tempting to answer this question by commenting on your character: "I'm hard working"; "I like to be challenged"; "I'm a perfectionist"; "I'm good at managing my time." While these answers suggest you have positive personal qualities, they don't actually answer the question. They don't explain how your presence will enrich the campus community.
The question asks about the community, so your answer should be community oriented. Think in terms of your hobbies and passions. What are you likely to be doing outside the classroom when you are in college? Are you likely to be serenading your classmates as a member of the acappella group? Are you hoping to start a D-League intramural hockey team for students who have never skated before? Are you the student who will be baking brownies in the dorm kitchen at 2 a.m.? Do you have ideas for a new recycling program that you think would benefit the college? Are you bringing your camping gear to college and looking forward to organizing outings with classmates?
In short, think about how you see yourself interacting with your classmates and other community members. The admissions officers have your grades and test scores, so they know that you are a good student. This question is your opportunity to show that you can think outside of yourself. A good answer illustrates ways in which you will enhance the college experience of those around you.