I am, admittedly, a podcast junkie. Half of my day at work is spent in my car, so I have my podcasts to keep me company.
In addition to Writing Excuses mentioned above (excellent), here are others:
I should be writing.
http://isbw.murlafferty.com/ Mur Lafferty's podcast on writing techniques and her own frustrations with the craft.
Authors Access.
http://www.authorsaccess.com/
Adventures in SciFi publishing
http://www.adventuresinscifipublishing.com/ This is more an author interview, and genera specific, but often topics are about publishing and writing.
Write the Book.
http://writethebook.podbean.com/ This is a catchall of writing. Much information is the 101 variety, but still good.
There are a few Grammar/Vocab podcasts I love:
Grammar Girl Quick and Dirty tips.
http://grammar.quickanddirtytips.com/ Ok, you probably know most of these grammar rules, but the pithy tips are so concise, and I enjoy the grammar discussion.
Grammar Grater.
http://minnesota.publicradio.org/radio/podcasts/grammar_grater/
Word of the day/etymology
Merriam Webster
http://www.learnoutloud.com/Podcast...MerriamWebsters-Word-of-the-Day-Podcast/19450
Podictionary
http://podictionary.com/
Wordsmart
http://www.wordsmart.com/landing/b/
Podcast by booksellers about new books. While not a how-to, they go into trends and why they like particular books.
Books on the nightstand
http://booksonthenightstand.com/
NPR in character
http://www.npr.org/series/17914370/in-character This is a limited episode podcast that goes into the great characters of literature, film, and folklore.
I hope you like some of these.