Kudos to Newsweek’s Jon Meacham for his essay on how thrillers and mysteries should get more respect as literature:

http://www.newsweek.com/2010/08/01/mysteries-thrillers-and-the-verities-of-the-heart.html
Much of the literature we now consider classic was the popular fiction, drama, or poetry of its day. Dickens and Twain were commercial authors. Shakespeare wrote to fill theater seats. Robert Frost appears in many popular poetry anthologies. Novelist and poet Reynolds Price wrote lyrics for James Taylor.

I once heard a creative writing teacher say, “If you want to write stuff that’s just for writers, write them letters.”