Charitydrives.org answers the questions:
Where can I go to get rid of all this junk piled up in the corner of the garage?
Where can I go to donate food/goods/clothing to a good cause?
How am I going to spread the word about my charity drive?
You can either search on the site for a charity drive in your neighborhood within a 10, 25, 50 or 100 foot radius, or organize your own charity drive. They even provide a 101 on Running a Charity Drive.
According to the site, Charitydrives.org was created in response to the needs of Hurricane Katrina survivors when its creator, Chris Seta, realized that there wasn't one site that listed charity drives across the nation.
When I did a search for charity drives within a 100 mile radius of the San Francisco Bay Area, the only results were 13 Salvation Army-Donation Centers. Seems like charitydrives.org needs to get the word out about their services, so help 'em out and let folks know about the site.