Historical Census Browser
The Historical Census Browser might help you put your ancestor's census data into perspective. Let's say you need the literacy rate in 1870 among white men over 21 living in Indiana. This site will tell you the number of reported illiterates in each Indiana county, and then will give you a map that offers immediate insight into their distribution. You can examine and map data in other categories as well, like employment, place of birth, and slave population. Looking at wage and employment data may explain why your ancestors left the farm to risk losing fingers in a factory.