Podcasting is an amazing way of connecting with visitors to your website because it offers additional content in a new format and it uses a subscription based delivery mechanism.
The upshot of this is that visitors to you site can subscribe to a Feed an will be automatically notified when you publish a new podcast, usually their software (iTunes or similar) will then automatically download the mp3 for them and let them know so they can listen to it on their iPod (it says here that other mp3 players are available apparently).
With podcast ranging from music to spoken word the limit of what you can do really is just your imagination.
Oh and of course we couldn't write about podcasts without mentioning that Adam Maxwell's Fiction Lounge won Best Podcasting Campaign at the North East Digital Awards in 2008. As the founder of Superhighwaymen Adam is unsurprisingly evangelical about how wonderful they are.