John Seavey at Fraggmented has a truly great ongoing series on the storytelling engines of classic comic books. (Via MeFi, which has the full list of columns so far.) Some highlights:

* How Aquaman works, or doesn't.
* The world-historical importance of the night Gwen Stacy died.
* Supergirl's Electra-fueled inferiority complex.
* Why you can't kill off Alfred the butler even if you try.
* Why they shouldn't have killed off Sue Dibney, even if it sold a few extra comics.
* Why Superman writes itself.
* And, of course, Howard the Duck.