By Tom Collins
If you're looking for free music to add to that cool video or slideshow you're working on, the first place to check should be Kevin MacLeod's site: Incompetech.com.
Kevin is a prolific composer, music score producer, and a big believer in the Creative Commons "By" license. He makes his creations available for free download, asking for credit on your production and allowing for voluntary donations. He provides an FAQ page, with details about the extensive uses he allows for free (including most commercial uses), instructions for giving him proper credit, along with the few wrinkles and exceptions.