I have said this before - iTunes Store has more than music etc. to buy, it has FREE content [Podcasts, both audio and video in nature, and iTunes U [for University] where you can download all sorts of edifying and interesting information. But the following blog comment explains it in more detail:
I had a interesting conversation with someone about my podcast. Mind you, this is a very smart person with an interest in computers and internet marketing. I mentioned to him that he should subscribe to my podcast in iTunes.