Marin County, CA Genweb Project a collection of online resources for genealogy researchers
Marin County, CA Genealogy Forum read and post messages about your ancestors for this county
Marin County Genealogical Society
Marin County Pre-1905 Calif. Death Index
Marin County Message Board read and post messages with other genealogy researchers of this county
The Tombstone Transcription Project - cemeteries for Marin Co. CA
US GenWeb Archives for Marin County cemeteries, newspapers, wills, military rosters etc recorded online

Additional Resources

California Newspaper Search enter your California ancestor's name to instantly search the world's largest newspaper archive; over 12 million newspaper pages
California Birth Records
California Marriage Records
California Divorce Records
California Death Records