Obituaries are one of the first documents that researchers will consult to find information about a family's history. Most often published in the deceased's local area newspaper, obtaining obituaries can require a substantial amount of legwork if all of the searches are done "in person".
To help alleviate this burden, many libraries and genealogical societies offer obituary search services. The requirements vary - some are free services, others charge a fee - and often there is an application to fill out in order for the agency to have enough information to attempt a worthwhile search.
Here are some links to a sample of the organizations in the Bay Area that will perform this service:
San Francisco Public Library Magazines and Newspapers Center - Obituaries/Death Notices
Oakland Public Library - Family History and Genealogy Resources
Alameda County Library - Frequently Asked Reference Questions
San Mateo County Genealogical Society (information available through Research Sevices link)
Santa Clara County Library - Obituary Searches
System Reference Center (BALIS/PLS/SVLS) - Fee Services
Marin County Library - Ask Us a Question
Contra Costa County Library - Obituary Request Form