Common Sense Media. Reviews of movies, games, apps, websites, TV shows, music, and books that are designed for young people, with links to online media. Here's a search on history media.
Directory of Public Libraries in the United States. Search to find your local public library. If you can't find your library there, try this list of U.S. public libraries. Even if can't visit your library, you can still use its website's online resources, such as e-books, music, videos, and homework help. All that you need is a library card, which is free.
Libby. An app that lets you borrow e-books and audio books from many public libraries. There are separate sections for kid books and teen books, and you can pick particular topics, such as "Biography & Autobiography."
Photo courtesy of Little Free Library.
Little Free Library. Here's a way to get free books without stepping inside a building. Little Free Libraries are colorful wooden boxes filled with books. People set them outside their homes or in public spaces. You can take books from the box, or you can give books away through the box. You can even build a Little Free Library yourself. Here is a map that you can use to see whether there are any Little Free Libraries near where you live.
This is a sample of the places I go online in order to do historical research. If you're doing research, you might find some of them helpful.
* The links that are starred require subscriptions or access through a participating library. Be sure to check the websites of any libraries you belong to, in order to see what electronic resources they offer you access to.
Search results from the Digital Public Library of America.
Digital Public Library of America.
Library of Congress (digital collections).
* Bookshare. See also the list of its participating publishers.
Google Books (advanced book search).
Library of Congress (catalog).
Fox Movietone News Collection.
* Kanopy (documentaries).
Library of Congress (prints and photographs).
Smithsonian Institution and Smithsonian Open Access.
Google Ngram Viewer (charts how popular words and phrases were in the past).
Old Maps Online. See also the list of its participating members.
USGS Historical Topographic Map Explorer.
Chronicling America: Historic American Newspapers.
* Historical Black Newspapers.
* Nineteenth Century U.S. Newspapers.
Old Fulton historical newspapers.
United States Online Historical Newspapers.
HathiTrust Periodical Collections:
H-Net (online forums for scholars, such as historians).
JSTOR (journals and books). See also how to get access.
BASE: Bielefield Academic Search Engine.
Elephind.com (historical newspapers).
HEARTH: Home Economics Archive.
ORBIS: The Stanford Geospatial Network Model of the Roman World. I'm waiting for someone to create a site like this for U.S. history.