Music and sound resources
So, where does a student or instructor who just wants to liven up their classwork go for music? Luckily, there are several possibilities available for worry-free music and sounds. (Educators and students can use clips and samples of music under the fair use provisions of US copyright. However, if you are uncertain, nervous, or wish to use sounds and music for non-educational projects, you might want to stick with the Creative Commons licensed materials.)
The first resource is one of my favorites, the Internet Archive Audio Collection. There are thousands of recordings here available for streaming and download. There is no overall copyright policy on these files; different artists have different policies which will be indicated in the records. The Open Source collection has Creative Commons licensing. But there are also collections of audio books, poetry, live music, news, contemporary music, radio programs and podcasts, even sermons, all of which should be available for "fair use" educational use. Someone interested in media studies can have a field day.
The second resource is Creative Commons itself. The Audio Collection is full of sound and music that people want you to use in your projects. It's amazing. I recommend the OWL music search for a fascinating search experience. Find a piece that's like what you want (including in your own collection). Then OWL will find more pieces like that one. You can also search by text keywords, but, in either case, be sure to use the check boxes for the appropriate CC license, as these are all general search engines and will retrieve commercial music as well.
CC licenses, whether you find them through CC itself or via any other search, specify how the creators will allow use of their creations. No further contract is needed, as long as you work within the terms of the license. Common licenses allow non-commercial use with attribution, or sampling with attribution, or even commercial reuse. There is also CCMixter, which is a mixing site featuring attribution-noncommercial licensed pieces available for reuse.
The Freesound Project is a collection of CC licensed audio clips for reuse, based at Universitat Pompeu Fabra in Barcellona. (I've been impressed with this collection before, but I can't get into it right now. Here is a little more about the project from CCMixter.)
There several sites that cater specifically to podcasters. Podsafe Audio maintains a collection of music licensed under Creative Commons and classed by genre. There are also ratings and reviews available. There is even a Collaborations site, which has pieces on which the artists are specifically requesting collaboration or assistance. On Podsafe Music Network you can listen to material on the site, but in order to download material for reuse, you have to register as a podcaster. This isn't really what you'd use for a one time project, but if you'd thinking of doing regular work, this could be a good option.
Of less interest to educators, there are also lots of "royalty free" music sites, where paying a one time fee will allow you to reuse the music over and over without paying additional royalties. If you are thinking of having a regular podcast or show, and can't find anything you like via the freely licensed collections, this could be useful. Here are a couple of lists to get started with: Podsafe Music by Sharon Housely and Royalty Free Music for a Podcast by Thomas Limoncelli (scroll down into the comments for more suggestions.)
Update (8/30/07): Here's an additional article comparing various big name online music stores' DRM-Free offerings: Finding DRM-free music online from TechCrunch. For those unfamiliar with the term, DRM is the protection system (or systems) that prevent you from playing digital files on "non-authorized" equipment. For instance, most iTunes files can only be played on the computer you originally downloaded the song onto, and music players hooked up to that iTunes (like an iPod)--with the exceptions noted in the article. DRM-free is not necessarily legally free for use, but it helps with the technical issues