Last time we had snow some guy I don't know came along and did my front sidewalk and the end of my driveway (for some weird reason if it's really windy the entire middle of my driveway blows clear--this is weird because the middle of my driveway is entirely boxed in by house/trees. Anyway...).
He has done my neighbor's driveway and sidewalk several times this winter. Today, my neighbor told me that he doesn't know this guy either. One day he stopped by and said to my neighbor (who is in his 80s), 'I see you and your wife out working on your yard all the time. I don't want you to have to shovel your driveway all winter. I'll do it for you.'
And he does.