Yes. There's a wealth of material out there which is either in the public domain or available under what is known as Creative Commons licensing, which generally means the work is available for free, subject to certain limited conditions, such as non-commercial use only and acknowledgment of the author.
For Creative Commons materials, visit the Creative Commons website for more information or check out their content directories which list audio, video, image and text materials available under Creative Commons licensing. For public domain material, simply search online for "public domain" and the type of material you’re interested in. Some useful sites include: Project Gutenberg (the largest collection of copyright-free books online) and Wikipedia, which has an entire page dedicated to public domain resources.