Although this book doesn't have simpleness in the title, it's another great book to get you thinking about how to downsize. With practical stories and advice for how to remove clutter (from your heart and home and schedule) this is one of the best books I have read.
Mark Tabbs simple and matter-of-fact style makes this an easy and good read. His goal was to help change your thinking, not just changing the outward things. I liked that. It made a much bigger impact and set this book apart.