When searching for data about Georgia and substate areas, CVIOG's own Georgia County Guide is a good starting point. It might contain the data you need, or the source notes might help identify potential sources for further investigation.
Government (state and federal) and independent websites and clearinghouses provide much of the data used in sub-state socio-economic research. Much of this data is freely available. However, below are some subscription-based resources available through the UGA Libraries which might be of use.
Provides decennial Census data 1790-present and American Community Survey data at least down to county level. Offers several non-Census socio-demographic datasets as well (e.g., church membership). Includes an easy to use thematic mapping component for use in creating presentations and reports ]
The Census Bureau's own website American Factfinder by contrast covers only the last couple of decennial censuses, as well as the American Community Survey and the Bureau's various economic data series (e.g., County Business Patterns, Economic Census, etc.).
PolicyMap maps thousands of periodically updated data points related to demographics, socio-economics, mortgages and home sales, health statistics, jobs and employment, education and more compiled from government sources as well as a few private sources. Sub-state geographic granularity varies. This is not a source for wholesale downloading of datasets.
ICPSR (Inter-university Consortium for Political and Social Research)
An archive of datasets both--longitudinal and snapshot--on many topics in the social sciences broadly defined including health care, criminal justice, government, demographics, elections, etc. Sources are scholarly researchers as well as government agencies. Some of the datasets provide state or sub-state granularity. Downloading is available to registered UGA users only. There is link at the site for new users to register.
iPoll (Roper archive)
iPoll is a search engine of the questions in the opinion polls contained in the Roper Center's extensive archive. Coverage goes back to the 1930s or 40s. Many of the corresponding datasets can be downloaded. The polls are mainly national samples only.
CQ Voting and Elections Collection
The Download Data section provides historical election results for Governor, President, U.S. Senator, and U.S. Representatives by county or district (Representatives). Coverage goes back to 1790 in some cases.
Proquest Statistical Insight
Proquest Statistical Insight is a database of titles and abstracts of government publications which contain substantial statistical content. As such it can be a useful way to identify possible sources of more extensive data either before or after using an Internet search engine. Many of the indexed publications are available digitally within the database as well. The database covers Federal sources, International sources, and State & selected independent research organization publications. For example, the Georgia County Guide is indexed in Proquest Statistical Insight.