Family Search labs has an online repository of texas death records from 1890-1976. Even though you can't save the files to your computer you can view a copy of the actual death certificate. If you don't have sources written down for death dates of any of your Texas ancestors this is a good place to go to validate your information and indicate your source.
Besides a death date and place, and burial information, The Texas Death Certificates also tell the birthdate, birthplace, father's name, mother's name & maiden name, cause of death, and sometimes even the spouse's name of each individual. They also tell the marital status of the deceased. Although the death certificates aren't always the most reliable of sources for information (other than death date), they are a great resource (an informant, normally the individual's spouse or child recalls most of the information).