Here are some things that I feel (keep in mind, I am not speaking on behalf of any school in particular,) a school might consider to be meaningful contributions to the student and school community.
Teaching: Perhaps you are a middle school teacher changing careers, or you have taught flute lessons to high schoolers, tutors students for the SAT, have TAed a class in college, or are a certified scuba instructor. Perhaps you (for no compensation,) teach piano to residents in a nursing home. Maybe you taught english in a foreign country, or you tutored high school students for their french class. In any of these cases, you have the communication skills necessary to confer your expertise unto others; this may translate to a skill you will call upon when educating your patient about their conditions, but in the nearer future and in context of what you bring to the table, you may serve your fellow MS1's and MS2's as a peer tutor should you develop a command of your courses sooner than your classmates or you may have a tendency to take the lead in small group sessions. Maybe you studied towards a MS in Pathology or Microbiology before starting medical school- you could discuss your accomplishment in the context of how it will help you lead others along in these areas of the preclinical curriculum, or perhaps contribute your free time to working in one of the schools labs, advancing its biomedical endeavors.
Service and volunteering: maybe you have a tremendous amount of volunteer hours, but only some are clinical and the majority are environmental or in other areas of your community; demonstrating your altruistic commitment to others, and the desire to shape your talents towards clinical medicine, perhaps you could discuss your interest in volunteering at the medical schools free clinic if they have one; maybe discuss a planned longitudinal participation, so that you may advance into a leadership position at the free clinic, and continue to serve your community, while also engaging others to do the same.
Foreign Travel, Foreign Languages, Multiculturalism: Disease is blind. Maybe you minored in African Studies, or you are fluent in Mandarin. Maybe you are Latino/a, and as an EMT, called upon your spanish speaking skills to consult and take a history from a spanish-speaking non-english speaking patient. Perhaps you speak french or Haitian creole and travelled to haiti to assist with disaster-relief in 2009/2010. Whatever may be your specific case, engage a discussion of your understanding of other cultures/peoples or your involvement in said cultures, and how this prepares you for a career where, potentially, you will on a daily basis be interacting with people from all corners of the world: an understanding of other cultures enables you to engage with others in a culture sensitive manner, which is valued greatly considering the blind eye disease turns to its victims.
Student Organizations: Maybe you started a nutrition club in college, or your were involved with a club that raised money to buy computers for students attending a poorly-funded/budgeted inner city high school. Maybe you held an officer position in a club that organized biotechnology entrepreneurship seminars on campus with guest speakers such as CEO's of fortune 500 companies or alumni that began start ups after graduating. Maybe you were involved in a pre-med club at your school, or were an editor for your schools student-research magazine. Whatever your specific case may be, you can discuss your involvement as a leader or as a member of a team, in the context of both participation as a leader and a team in healthcare (doctors leading a department, but at the same time, working together as a member of a team alongside a nurse, pa, or nursing assistant, respiratory technician,etc,) and continuing to foster team-building and leadership in self and in others through participation in clubs at that medical school; look on their website, maybe there is a club that really interests you that you could discuss your potential involvement and what ideas you might want to bring to life through that club.
Research: maybe your school divides the incoming class into sub-communities (5/6 students assigned to a faculty mentor, or something like that) - your group may be assigned a research project for a course or as part of 1st/2nd year curriculum - if you have previously been involved in research (research assignment for a lab class, senior thesis, summer internship, research assistant or lab tech after college, etc) you could discuss your talents and skills in research as something you expect to call upon when doing your group project; maybe you have more biomedical research experience than your peers, and you could lead the effort and guide/shape the skills of others, helping them grow into better student-investigators: clinical diagnosis, too is a type of investigation, so the ability to research something in the lab or for your project could be skills which translate to your skill set as a doctor as well.
These are just a few ideas that I had, off the top of my head. I should give a disclaimer, that I did not write these in the context of my own experiences or things I have done - some things I have been involved in, though not necessarily the identical examples I have given here. I am sure there are other things that would be considered meaningful contribution to the student community, so please do not take their omission to be judgement for non-involvement in the examples I give here.
