Most people focus on podcast advertising as the main revenue stream from their podcasting efforts. Consider offering podcast consulting services as a way to earn a stream of revenue from your podcast.
If you've been podcasting for a little while and are very familiar with the tools, services and the podcast industry in general then chances are that businesses can benefit from your knowledge. In fact, you probably know more than you think you do.
I've met with a lot of business owners who are very excited about podcasting, but don't have the time to navigate all the steps required to create, publish and promote a podcast. I've earned money doing this and I can tell you that the opportunities definitely do exist.
A great way to get started and build a reputation is to approach non-profit organizations in your community and offer to help them with creating a podcast (or even just a blog) on a pro bono (yes free!) basis. They cover any costs related to actually starting the podcast (like hardware, hosting, software) but you don't charge them for the time to do the work.
This approach serves two purposes. First, it helps you to gain experience working with clients which can be very helpful if this isn't your normal cup of tea. Second, you have just added a friendly client to use as a reference when you make proposals to other businesses.