My favorite is Writing Excuses. It's hosted by Brandon Sanderson and two of his friends. Brandon is a writing professor as well as an author, and it shows. While it covers all aspects of writing fiction, it tends to focus heavily on fantasy (as that's Brandon's forte).
The only podcasts I've listened to in recent years have been from the Decoder Ring Theatre - The Red Squirrel and Jack Justice. For some reason they tickle me, though I can't put my finger on exactly
why.