unfortunately the topic is quite a "popular" one-- prolific one.

There is an annual radio program called the Homelessness Marathon.
It is a 14 hour program that airs each year...in Feb. i think...and here are some of the songs I play during it..
Homeless by Lou and Peter Berryman it is on page 4 here
http://www.louandpeter.com/allsdlyr.pdf

Sarah Elizabeth Campbell's song Geraldine and Ruthie Mae can also be
heard on the wonderful Women's Bluegrass Group album Blue Rose

here is a whole long list of songs about homelessness
http://nwfolk.com/songlists/homeless.html

http://www.amazon.com/HOMELESS-AMERICA-Twenty-One-Conscience-Century/dp/B000BGQSZE

here is a touching song on you tube--and many others show up in the
selections...http://www.youtube.com/watch?v=c5Gu1r6A3VE

there is also a christmas song album of songs being sung by homeless
people i can't find it right now...but I'll look for my copy and post]