If you don't already know, podcasts are audio (and/or video if you have one of the newer iPods) broadcasts usually lasting anywhere from a few minutes to an hour or longer each. These broadcasts are made available as mp3 files for downloading. Most podcasts are free (although some Air America Radio's podcasts require you to subscribe to their premium service). Podcasts allow you to listen to the content independent from any set schedule (perfect for long trips or commutes).
You can automatically get the latest podcasts from many sources using a 'pod catcher', there is one in iTunes and several others are available on line. Just enter the subscription url (or choose the subscribe button in iTunes) for the podcast(s) you want.
Among the free podcasts available which I highly recommend are:
Governor Mark Warner Audio Podcast:
http://feeds.feedburner.com/markwarneraudiopodcast
The Clarkcast with Wes Clark:
http://feeds.feedburner.com/clarkcast
U.S. Senator Barack Obama Podcast:
http://obama.senate.gov/podcast/index.xml
John and Elizabeth Edwards' Podcast:
http://www.oneamericacommittee.com/podcast.xml
U.S. Senator Russ Feingold Podcast:
http://feingold.senate.com/news/podcasts_index.xml
(this one has been down as of late)
Ring of Fire with Robert F. Kennedy Jr. and Mike Papantonio:
http://www.ringoffireradio.com/podcast.asp
Mother Jones Radio:
http://www.motherjones.com/radio/rss.xml
The Young Turks:
http://www.theyoungturks.com/yturksfeed.xml
Any or all of these will help keep you informed and insure you always have something fresh in your player.
Many more podcasts are available, several hundred podcasters are generating content from their homes.
Check it out...