You mention volunteering at a homeless shelter, well one of the things my wife and i did was to walk dogs at the RSPCA. My wife and I are dog people and due to the moving and housing solutions in Defence we found ourselves unable to have family pets for periods of time. In order to get our 'fix' we used to go to the RSPCA and walk dogs. It was great fun. The people really appreciated it and so did the dogs. This is something a single living-in member can enjoy or something for the whole family. Just don't get too attached or you may be bringing one home.
Luke