Books We Own is a list of resources owned/accessed by individuals who are willing to look up genealogical information and e-mail or snail mail it to others who request it. This is a free service - volunteers may ask for reimbursement of copies and postage if information is provided via snail-mail. The project began in 1996 as a way for members of the ROOTS-L mailing list to share their resources with one another. Today, there are over 1500 volunteers.The resources on their Website are organized by country and by family. The U.S. resources are further organized by religious groups, native Americans, Mayflower resources, Revolutionary War, Civil War and other historical events. There is a further regional organization.
Some of the lists are pretty sparse, but others have dozens of reference works that could be consulted. It is worth a look at this site if you do not have a reference library close at hand. But I would also check the Family History Archive, Google Books and other on-line resources of digitized books.