Short of a youthful longing to run off to Africa or india or somewhere else exotic and house the poor, most of my service aspirations are domestic and local. Homelessness in general has been a cause of mine since I was 16. It is amazing how close even the most stable professionals are to being on the street.
Since then it has become wider in that I want to actually solve the root problem and not just put a band-aid on it. In college I worked with a couple organizations that worked on just that.
Currently I am considering doing something along the lines of community development of transitional housing and programs to solve the problems that perpetuate homelessness.