If you still want to purchase something....
I purchased this book last summer
Amazon.com: The Photographer's Eye: Composition and Design for Better Digital Photos (9780240809342): Michael Freeman: Books
It focus on the composition side and the "art side" of photography instead of the ususal triangle / exposure (ISO, Aperture, Shutter). I found the book very interesting and providing information I wasn't use the see everywhere.
A very good investement IMO.