There are a number of excellent guidebooks that can help you plan your trip to Machu Picchu and the rest of Peru. A few titles to look out for include:

The Inca Trail, Cusco & Machu Picchu (3rd Edition) by Richard Danbury and Alexander Stewart -- this guidebook is invaluable if you plan to hike the Inca Trail. In addition to a step-by-step description of the trail, the book also includes general travel information to Peru and the Machu Picchu region as well.

The Machu Picchu Guidebook: A Self-Guided Tour by Ruth M. Wright and Alfredo Valencia Zegarra -- this guidebook is indispensable when it comes to walking around the ruins and actually understanding what you are seeing. Not only does the author describe what you are seeing as it is today, but she also describes what it might have looked like during the height of the Incans time at Machu Picchu.

If you're looking for some pre-reading about the area's history and archeology, a few books to look for include:

Lost City of the Incas by Hiram Bingham -- this a must-read for those planning to travel to the Lost City, as it is written by the Yale archeologist who 'found' Machu Picchu in 1911.

Machu Picchu: Unveiling the Mystery of the Incas by Richard L. Burger and Lucy C. Salazar -- this book features information about what archeologists have learned about Machu Picchu since Hiram Bingham discussed his theories in his book. A number of new and archival photos help to bring the region to life.