There are free places online for people to actually download MP3s on any subject. Naturally, you can also upload them for free.
Many people are audio-centric and prefer to learn by listening on their iPods, usually so they can
multitask or not be bored during a commute. Giving them free content is an excellent way for your name and relation to their favorite subject matter to be presented.
Much like how an article works, effective PodCasting depends on your content being interesting enough for them to want to download it, but at the same time, you must include your sales message and of course end it with a “Call to Action” that motivates the listener into following up in some way such as visiting your website.
It’s true that this rarely results in many links back to your site, and if your content is interesting enough, the best you can hope for is for fans to pass them around to each other by word of mouth… Certainly no benefit for link-building.