The US GenWeb Project is a wonderful, free tool for anyone doing genealogy research. There are links to each State, and from there each County should have its own site. The county sites are maintained by volunteers, and some counties have not yet been adopted. There is a lot of good information on this site, so check it out by clicking here.
As for my particular line, the following county sites are worth taking a look at:
Missouri
Schuyler County Missouri
Ohio
Meigs County Ohio
Lawrence County Ohio
Gallia County Ohio
Vermont
Orange County Vermont
Massachusetts
Essex County Massachusett