The USGenWeb project is one of my favorite free resources to use online. From the main page you can jump to one of the 50 state pages. From there you can select one of the many county pages for your state. These pages (really sites unto themselves) are maintained by dedicated volunteers with a wealth of knowledge about their local area.
Many of the counties have various cemetery transcriptions, family histories, war records, property & tax records, local census records and much much more. Many of the volunteers are also willing to look up local information you may not be able to get access to from out of the area or online..
I’ve used the pages for Missouri and Iowa and had great success. Try looking through the area you’re currently researching and see what you might find.