The Ever-Growing Online Library of Congress
The online collection of materials at the Library of Congress continues to grow at a phenomenal rate. If you visit their online collections at memory.loc.gov, you will find text, images, sound files, and now video files. You can search the hundreds of thousands of files by keyword, or browse the collections by topic, such as the Civil War, the Depression, Early Animators, or many others. It’s an amazing resource, and all of the files can be downloaded for use in classroom presentations.
(A footnote - at this moment on Sept. 18, the site is unavailable, probably due to Hurricane Isabel and the closing of all federal offices in Washingto D.C. If you can’t get in, try again on another day. Assuming they aren’t washed into the Potomac.)