If you are digging into your family history, then you're a researcher at heart, which means -- almost by definition -- that you love libraries. But many old-fashioned library-lovers haven't yet fully explored all the free online resources that libraries make available these days. There are some great online library tools for family history research, starting with...
WorldCat. True to it's name, this is an enormous catalogue of 1.4 billion items from more than 10,000 libraries around the world.
WorldCat is a useful family history database in its own right -- a search on your family surname, or on a particular individual, may well turn up new information. Beyond just author, illustrator, editor names, this enormous database includes millions of names of people mentioned as subjects in books. You may be surprised at what you find.
Reading Room, NY Public Library
And of course, WorldCat is also a book-finder, showing you which libraries carry a particular item you're looking for, and even sorting them by distance from your hometown (but if you don't want to make the trip, ask your local library to arrange for an interlibrary loan).
Your public library is another fantastic online resource. Most libraries subscribe to numerous databases, including history, newspaper archives, and genealogy services, that patrons can use for free. My local library, for instance, offers links to Heritage Quest, Historic Newspapers, several Whos Who, and people-find service like Reference USA. All for free!
And if your local library doesn't have the database you need, there are ways to access the subscription resources at other libraries, across the state, or across the country. Check out this article on remote access to subscription services at public libraries.
Visit the main page of Free Genealogy Tools for more, umm, free genealogical tools.
See if your library has free access to Ancestry.com and NewspaperArchive.com. These are subscription databases, but they are among the most powerful research tools available for looking into family roots.