I always figured a low-cost/high-impact charity would be free PO boxes for the homeless. Then you have a fixed address you can put down for a job application,

I always figured a low-cost/high-impact charity would be free PO boxes for the homeless. Then you have a fixed address you can put down for a job application, getting through that filter, and it can be used to bootstrap access to other social services (For example, Medicaid programs that require regular renewal-- where do they send the renewal form to someone without an address?)