A local non-profit organization that I think is so crucial, yet based on such a simple premise, is Community Voice Mail. They started in Seattle and have expanded around the country.
CVM provides voicemail service to people in crisis. It might be a homeless person who's trying to get a job and needs a way for an employer to contact him. It might be a woman leaving an abusive spouse or a homeless, runaway teen trying to find a home, a job, whatever. Having a phone number of your own can be empowering when you're in a crisis. For example, you don't want your family or a potential boss calling you at a shelter.
Check out the website and consider supporting them.
"Turning phone lines into life lines"