The Flytier's Benchside Reference. This hefty tome gets a special place in my tying library.

No patterns or recipes, just 100's of detailed tying techniques. I have had my copy for over 5 years, and I am still reaching for it on a regular basis. Add the Umpqua pattern book and I think you could tie anything.

It's a large pricey book, lot's of color photographs I paid arounf $100 for my copy. I have heard of internet deals as low as $60.