I have been listening to Grammar Girl a bit and I like her. Her voice is not all that inviting but what she has to say is relevant. In one that I listened to she was sharing info on the correct way to use shall and will and comparing the American version and the British version of what is correct. I think that my students would find this interesting. Another one that I found helpful was a talk about attribution in writing. She shares several examples of how and where to put these in sentences. I feel that I will really have to pick and choose with her casts (I’m not thrilled with all of them) but if I can keep up with my reader regularly, I think that I will find some that I can use.
Or maybe you could get students to create their own “hipper” grammar podcasts!