Sources => Web Sites => Other Resources:
Most of the census images were downloaded from Heritage Quest Online. While this is a paid access site, your public library probably has an institutional membership which you can use. I can use mine from home.
The Family Search web site (free) has an excellent search engine.There are many very useful databases here, including many state VR and state and US census. This site is a service of the LDS Church.
The New England Historic Genealogical Society has an excellent site, some parts free, and some parts paid access. Again, your library may have an institutional membership.
I'm sure you're familiar with Ancestry.com, which has the only searchable index I've found for the 1930, 1940, and pre-1850 census. The library's institutional access is somewhat limited, however, and you need a personal subscription to access the entire site.
The Civil War Soldiers and Sailor's database.
The World Connect Project site is very useful to search for specific names of interest posted by others (use with caution . . . . . )