Payback is the fourth Margaret Atwood book I've read in as many months, and although I doubt it would appeal to anyone but the most devoted Atwood fan, it is a playfully-written and unexpected exploration of what she calls the "human construct" of debt.
The book is divided into five forty-page chapters, each of which could stand as its own essay. The first of these traces the concepts of debt and repayment back through time and finds, in the study of primates, the instinctual inclination to borrow from, and later repay, perhaps with back-scratches, one's comrade. In the remaining five chapters, Atwood backs away from history and science and relocates herself in the more comfortable (I assume) field of literary criticism, where she explores debt's connections to religion/sin, revenge, and in particular the Nineteenth Century novel. I realized early on that Payback was not the book I thought it was when I ordered it from Amazon -- I was looking for a more philosophical tome that would help me with the current high school debate topic -- but nevertheless it was a fun read.
On another note: If you're a teacher and use Dickens's Christmas Carol in your classroom, you should photocopy and share with your students Atwood's modern-day parody -- "Nouveau Scrooge" -- in which an unlucky 21st-Century Ebenezer is carried back and forth through history by the ghosts of Earth Day Past, Present and Future.