As an avid podcast listener and business & technology fan, I began developing this idea a few years ago. I’ve called it "PodNet", short for Podcast Network. Here’s the quick-version of what it is; Combine the old Napster / file sharing idea with an affiliate program and the SETI program. There are a few pieces to the plan, but for those who don’t understand how podcasts work in general, here are simplified explanations for 
how a content consumer and a content creator use podcasts:
Note: A podcast is nothing more than an MP3 file (or MPG for video podcasts). 1 hour of (spoken word) audio can be about 50mb.
Content consumer
User with portable audio devices (smartphone, Android, iPod, Zune, MP3 player, etc.) use a download manager (iTunes, Google Listen, gPodder, etc.) on their PC to automatically retrieve content that is frequently updated. For example, if they subscribe to the Adam Carolla podcast, the download manager reads an XML file to see what the current episode is, then downloads it and copies the file to their PC. The download manager is scheduled to check that XML file on a regular basis for new episodes and downloads as they become available. Then, when the portable audio device is connected to the computer, that downloaded content gets copied to the device for playback.
Content creator 
To stick to the Adam Carolla example, Adam creates a new episode every day (for the most part), and uploads that 30mb to 60mb file to a web server, then updates the podcast XML file (the file is like a catalog that gives the title, length, description, filename, etc. of the episode). As podcast management software reads the podcast.xml file, it downloads the file from a web server.
Web servers are the computers on the internet that "serve" a webpage or file. As each podcast (MP3) file is downloaded by a user’s podcast manager, the web server keeps track of how many megabytes it serves to users. If you’re Adam Carolla or NPR, you could be paying for thousands of gigabytes of transfers (also called bandwidth) each month – 1 podcast @ 50mb x 100,000 downloads in a month = approx. 5,000,000mb (~4.7terabytes). Web hosts usually charge the content creator by the amount of bandwidth they use, so the more popular your podcast is, the more it could cost you.
Adam Carolla, Kevin Smith, NPR, Ricky Gervais – these are some of the most downloaded podcasts on the web, so they’re paying a lot of money to get their content out there. In the television world, the cost of producing and broadcasting a TV show is offset by selling commercials. Most podcasts have few (if any) commercials, so the content creator has to foot the bill.
Enter PodNet.
Okay – almost… but before explaining PodNet, review these two distributed systems:
File-sharing services from years ago (or torrents from today) would take a single file – a video, mp3, game or program file – and break it up into smaller pieces. So let’s say a 50mb MP3 file is broken into ten 5mb pieces. Each of those pieces would get downloaded by the file-sharing software on various users’ computers then reassembled to the original 50mb file. Then those user’s computers would in turn serve several of the 5mb pieces to other file-sharing users on the web. Repeat that millions of times, and the load on the original web-server is reduced to almost nothing (assuming enough people are downloading the files.)
SETI@home is a distributed system that utilizes the "unused" processing power of computers that are connected to the internet, but which aren’t doing anything (like your home computer that is on while you’re at work or sleeping.) You install the SETI software on your PC, and it downloads a file containing a chunk of data collected from radio-telescopes, then analyzes the data for patterns. The software then sends any significant data back to the scientists for detailed analysis.
PodNet would combine some of these and other elements to create a new distribution system for podcasts. What makes PodNet different from normal file-sharing software is the affiliate payment aspect.
PodNet Problem Statements
- Content Creators must pay high monthly costs for bandwidth to serve their content.
- Non-commercial internet users (Home and small businesses) generally do not use the bandwidth they are paying for each month.
- Computers that are always connected to the internet, but which aren’t being actively used have great potential for distributed systems.
PodNet Offering
The PodNet service redirects requests for downloads to "PodNet Mini-Servers" located all over the internet, rather than the Content Creator’s web servers, thus minimizing their bandwidth costs.
PodNet Redirection Service
When download manager software initiates a request for an updated XML file to check for updated content, the Redirection service returns a dynamic file which changes minute-by-minute, based on various data points. A master status database stores continuous status information as reported by Mini-Servers. The Redirection Service builds the dynamic file based on the content requested and which Mini-Server would provide the best access to that content at that moment.
PodNet Affiliate Program
Affiliate programs generally allow members to get small payments for referring a product or service. The PodNet Affiliate Program would pay participating members for serving podcast content from their PCs. The most content they serve, the more money they make.
PodNet Mini-Server 
The PodNet Mini-server is a very small application that runs in the background and communicates with the PodNet Redirection Service to coordinate serving content. The user has control over what hours content can be served, how much bandwidth to use by day/week/month and which content they want to serve. The Redirection Service reports overall usage which is used to calculate Affiliate payments (if the user has chosen to join the Affiliate Program.) The Mini-Server reports what the available connection speed is, what content is available, how many files have been served, how much time each transfer has taken, what IP address downloaded the content, start and end-times and other technical data to insure that content has not been tampered with before being served.
Obviously security, transfer rates, file sizes, throughput, tracking, usage and many other details are not included here, but that’s the basic idea. And yes, this idea could be akin to torrents, but on a “legal” and more automated scale. I’ve also looked around at ISPs to see what restrictions there are to running file servers over your home internet connection, and the main thing I find are rules against pirated content. In the case of PodNet, all the content is legally distributed.
As more media channels move to “anytime content”, the need for legal, lower-cost, distributed file-sharing is going to grow. PodNet may be one way to reduce costs while increasing availability.