The father of ultra-light: Ray JardineI recently received a copy of this book for my birthday. Ray Jardine is one of the original figures in the lightweight and ultra light weight hiking movement.
A veteran (with his wife) of most of the long distance trails in the United States, this book is an explanation of the methods and equipment he utilised walking long distance trails such as the Pacific Crest Trail and Appalachian Trail.
He has termed this the "Ray Way", a overarching method to travel further while carrying less.
Although this book is older (late 90's) and focused on the American hiking fraternity, I think it still has a lot to say for all trampers/hikers/ramblers regardless of their location. The main message is: travel light, steer clear of hauling the kitchen sink with you in the outdoors. It also has a strong environmental message about minimising our impact on the trail.