Ok, all discussion of why you would want to learn it, or how much use it is in 2012, aside.........
I did actually at a point in my life in a moment of lunacy and romanticism learn Celestial Navigation. When I asked around the book that most of those in the know recommended was celestial navigation for Yachtsman by Mary Blewitt.
It certainly proved very helpful. Other books I read were either too detailed in ways unnecessary for what is required or just difficult to follow. This book I found was the most concise easy to follow guide.
Hey if I can learn Celestial Navigation from this book then anyone can