Elizabeth House Provides services and shelter to women in difficult situations... (located next to St Augustine's in what I think is the former convent.) There are a variety of opportunities here.
Berkeley Food and Housing Project Among other things, they have a Women's Center that serves homeless women and families and women with disabilities through a temporary shelter, transitional housing and other services.
Night on the Streets Catholic Worker -- lots of services (click here for a comprehensive list) for the neediest residents of the East Bay, especially around Berkeley. [I have worked with the Sunday morning breakfast for the homeless (starts at 7:15 am in People's Park every Sunday) and the soup and hot chocolate delivery which happens several nights each week in the winter months. Contact JC Orton (info at link above) to get involved, or just show up on Sunday morning :-) ]
Oakland Catholic Worker -- primarily serving the migrant community -- opportunities to tutor English and work with the clients in other ways and I don't know what all else-- they always need people to help!
International Rescue Committee Oakland branch -- helps resettle refugees and provides other services for refugees
Planting Justice-- urban farming resource, food justice, etc., also teaches permaculture skills to local prisoners with the goal of hiring them when they are released and volunteers teach high school students about gardening and food justice issues... a very interesting grassroots group
St. Anthony Foundation in SF has a variety of ministries (meals, clothing, employment counseling, etc.) that always need volunteers.
This organization holds workshops every few months, usually on a Saturday (but sometimes on Sunday) where people who are trying to become naturalized citizens can come and get help filling out their paperwork, talk to a lawyer, etc. [I really enjoyed helping out at this.]
Bay Area Literacy looks like a great program -- I volunteered in a similar program in Charlotte, NC, and enjoyed the work very much. (And I'm thinking this might be a good place for me to plug in to help someone with GED prep -- I promised a friend I would do this so I'd better make good on my promise...)
- Volunteer Center for the East Bay; as an example, here are links from there to Education opportunities (I put in my zip code (94609) and a 10-mile radius)
- Bay Area Volunteer information Center
- Catholic Charities of the East Bay -- a couple of times a month they have a"Transforming Lives Tour" that gives comprehensive information about their projects and programs.
There is also a list of opportunities in and near Berkeley here.
*if you don't live in the Bay Area, I hope this list will give you some ideas about what you can do in your own community to reach out and get involved!