From my experience with Georgia (state) genealogy research, the most readily available marriage records are the Marriage Books kept by the county clerk of the Superior Court. These books record marriage licenses and go back to 1805 when they were required by law. They are, for the most part, fully available on microfilm at the Georgia Archive and online at GeorgiaArchives.com and FamilySearch.org through the early 1900s.
If you dig a little deeper, often visiting a local courthouse, you might find Marriage Bonds as well. These are often "loose" records and are likely to have been microfilmed, however they don't provide information on the actual marriage and are thus not as likely to be found online.
Marriage Bonds represent a groom's intent to marry and his promise to pay a penalty if he backs out or it's discovered that he is not eligible to marry. The best thing about the marriage bond is that it is co-signed by another person, often a relative of the bride. Their name might help uncover the bride's family. These bonds are not proof that a marriage occurred however, so you should rely on the Marriage Books for real evidence.
Images: Top: Marriage License of George Craft and Effie Powell, recorded in "Elbert County Marriage Book, 1882 - 1893." Bottom: Marriage Bond of Moses Craft and Nancy Hudson, stored in Elbert County, "Marriages box M1 1802-1808."