Your local public library, university library, or Family History Library may have access to databases or subscription services that could be helpful in your genealogy research. Besides Ancestry.com, GenealogyBank, Footnote.com, consider academic journal indexes and databases, Sanborn Fire Insurance maps (often through Proquest), and other "non-genealogy" materials. You might be surprised at what you find.
And learn how to search effectively--search for not just names, but places and locations where your ancestor lived. It might be that someone has done doctoral research on an area where your ancestor lived, an ethnic group of which your ancestor was a member, etc.