If you ever use sound effects in your podcast, I recently found a cool resource for free, legal sound effects: soundsnap.com. The site has a very intuitive interface, and offers downloads without having to register. An advanced search function allows you to search by keyword or from a list of categories.

If you are doing radio style drama in your podcast, or just looking to include an occasional sound, soundsnap seems like a good way to find quality sounds without having to pay royalties or other fees. Although the site's focus is on effects, there is also a category for music loops, of which there are currently over 9,000. The quality of the sounds that I have tested was quite high. Happy hunting!