In a potentially useful contribution to Simpsons research, the authors have constructed an annotated bibliography of essays, books, and other types of research about America's Favorite Cartoon Family.
I'm delighted to find that an essay I co-authored with Anne Marie Todd, "'Are We There Yet'? Searching for Springfield and The Simpsons' Rhetoric of Omnitopia," is cited. Moreover, a decent amount of material from the book is available via a Google Books search.
Teaching (or taking) a course that addresses the show? This book might be worth a look.
Visit the authors' Google Site: Simpsonology 101