The San Luis Obispo County Genealogical Society has been hard at work for many years as evidenced by their website. You will find an index to Naturalization Records, Original Plat Maps from the Spanish Land Grants, Indexes to land records, tax records and civil court cases.
Vital records include indexes to delayed birth registrations, marriage records, church records, obituaries and mortuary records. Additionally there is a large collection of cemetery records, indexes and readings. Some photographs are available online, others can be attached to an email upon request. Assorted voter registration records are available spanning the years 1867 to 1944. Rounding out the collection are biographies and news articles of genealogical significance.
At least one case there is a link to images that are available on FamilySearch. The index provided by SLOGS will help you find the record you want.
Enjoy as you work your way through years of volunteer effort on the SLOGS website.