San Diego County, CA Genweb Project a collection of online resources for genealogy researchers
San Diego Genealogical Society 
San Diego County - American Local History Network has several pages of information for this county
San Diego County, CA Genealogy Forum read and post messages about your ancestors for this county
San Diego County Message Board read and post messages with other genealogy researchers of this county
The Tombstone Transcription Project - cemeteries for San Diego Co. CA
US GenWeb Archives for San Diego 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