What is a good podcasting mic?

I'm by no means an audio expert, but I have a buddy who's been happy with his Blue Mic Snowball mic. He uses it to record music in GarageBand. It's supposed to be good quality for the price (~$100).

I'd say it depends how you define "good." The Blue "Snowball" is a good inexpensive podcast-centric mic. It's USB connection does not require a mic preamp, yet should provide better performance than the 1/8" mic input on your PC.
I personally use a inexpensive USB mic preamp (M-Audio "Fast Track Pro") with a nice cardioid mic (Neumann TLM103).

I second the thumbs up on the Snowball. I was never an avid podcaster but I did work for a podcasting company (Odeo) and that was everyone's favorite.

My personal favorite is an iriver, but only because it fits in my pocket and is more likely to be with me when I want to do a quick interview.

You may also be interesting in the question I asked: http://www.fluther.com/disc/522/whats-a-cheap-good-microphone-setup-to-record-on-my-mac/

I did look at the Snowball, but was a little turned off from the USB interface because 1) I can only use it with my computer (I may want to use my mic for other creative projects) and 2) Since USB isn't that fast, it can create a delay in the audio feedback. But I'm sure it's fine.

I have a list of all the Tools I use http://www.schoolofpodcasting.com/tools I’m not a big USB fan, and I like the AT 20/20. You just don’t want the $30 headset mic. Your mic is the most important part of your audio chain.