There are so many out there it is hard to recommend just a few. As Carlton said it does depend on what you like.

I listen to Escape Pod and Pseudopod as well although I'm way behind.

I recently started listening to one called "The Race to '08" from CNN. It's a quick podcast (about 2 minutes that discusses real quick what is going on the presidential race.

Some others I listen to:
MacCast, TWIT (This week in Technology), Cranky Geeks, Boagworld (a web design podcast), and Skydive Radio.

Warning!: Podcasts can be addicting and if you listen in your car you may forget about those other crappy radio stations.