I'm so impressed with Grammar Girl's Podcast, which has already taken multiple awards, that I'm recommended her upcoming July 8 grammar book.
I love podcasts on my iPod, and playing them in my car while traveling. Since budget demands have cut down my pleasure driving, I'm getting a iPod player that recharges and I can listen at home when I want.
I'm very enthused about several podcasts, so far as writing goes, The Writing Show and Writers on Writing, both of which have wonderful material, including interviews with all sorts of writers, agents, etc.
What am I listening to now? is a usual post. To date, everyone else's has been music. Mine are podcasts :)