Matt Slick's podcast is great. It was from that that I first learned of the Doctrines of Grace and verses supporting eternal security. Recently I've been listening to The Comfort Zone with Ray Comfort. It's the audio version of his web show which is broadcast live on The Comfort Zone Live and can be watched later on YouTube. They deal with current events and also answer questions that people send in. Also worth a look is Wretched Radio by Todd Friel. You can get a short segment (around 15 min) for free, but the full 2 hour show (which is streamed live for free) costs $5.95 per month to get the podcasts.