Not all volunteering needs to be in a hospital. Think hospice, Planned Parenthood, nursing homes, rehab facilities, crisis hotlines, camps for sick children, or clinics.
Some types of volunteer activities are more appealing than others. Volunteering in a nice suburban hospital is all very well and good and all, but doesn't show that you're willing to dig in and get your hands dirty in the same way that working with the developmentally disabled (or homeless, the dying, or Alzheimers or mentally ill or elderly or ESL or domestic, rural impoverished) does. The uncomfortable situations are the ones that really demonstrate your altruism and get you 'brownie points'. Plus, they frankly teach you more -- they develop your compassion and humanity in ways comfortable situations can't.