H-CIVWAR - a discussion group on teaching about the Civil War (Michigan State University)
University Publications of America Their guides point to a lot of original material, not just on the Civil War. You would need to find libraries with that material though.
Civil War Information, Documents, and Archives - I can no longer find this site. Any one who can help, please let me know.
Search within the above links
By double clicking on the above links, you can search that link's site for