There's a rather ambitious project called waybackmachine with the aim to archive the web. It sounds impossible, but the makers really have stored billions of pages trying to make this a “universal access to human knowledge”.
Besides archived webpages you will find a lot of free audio files, movies, even complete live concerts for download.
Be sure to have some time left when visiting the page. It took me several days to get an overview of only a very small part of the contained information.