You can post Podcasts on your website or on Podcast directories where they can be sold or given away. Posting them on Podcast directories provides a chance for people find them there and visit your website if they like the Podcast but the directory also provides a backlink to your website and Podcast directory home pages often have a high Page Rank.
List of Podcast Directories
List of over 80 podcast directories
Posting Podcasts to your website
You can also post Podcasts to your website. These can simply be an audio version of an article or articles on your site or it could be a recording of an interview or radio advertisement you have (a great way to use old collateral material and content).
There are a lot of Podcasting tools out there, and of them are free, to help you create and post Podcasts. You can personally read and record your articles, have them converted to audio electronically, pay to have a professional voice over read them and record them or even strip the audio portion out of a video.