Good responses already about materials. But some books I've found useful. Dick Talleur's "Modern Fly Tying Materials" http://www.booktrail.com/Fishing_Ties/Modern%20Fly%20Tying%20Materials.asp
and Eric Leiser's : "Fly-Tying Materials" http://flysupplies.virtualave.net/Books/leisersc.jpg Leiser's book is more about natural materials.
