Let's start with this page that has most of the links for where to find information about State and County birth, marriage and death records from around the USA - FreePRF.com's Birth, Marriage & Death Records page.
If you are trying to find the birth date of the person you are researching, I suggest trying this site that has a free birth date lookup - BirthDatabase.com. BirthDatabase.com is a pretty good resource for finding the exact year, month and day of a person's birth. The best part is that it's FREE. The only fallback with this site is that you can't narrow your search by state. The search results cover the entire USA for all the persons with the name you area looking for. Some names are omitted from this database.
For birth information, Ancestry.com is another good resource. It also has a death records database.
Marriage records are tricky, especially if you want information from California. Most recent marriage records in California are confidential. You can obtain some information from VitalSearch.ca; however, those records only go up to 1986. They also have a database for California birth and death records from 1905-2000.
Vitalsearch-ca. also has a marriage database for Texas. Their Texas marriages database is comprised of over 6 million groom/bride entries from 1967-2007. In addition to California and Texas, Vitasearch-ca covers several other states and has a reasonable sign-up fee. I suggest that you do not log-in as a guest because you will have a restricted view of the data.
If you cannot find the vital records information online, try The National Center For Health Statistics page on "Where to Write For Vital Records." It lists the mailing addresses, phone numbers of all the states vital records offices and how to obtain such records.
