The following is a list of helicopter-related books that I own. I've even read most of them.

TRAINING

How to Fly Helicopters (2ed)
Larry Collier, revised by Kas Thomas
1986, 0-8306-0286-0
TAB Books

Flying the Helicopter
John J. McDonald
1981, 0-8306-2326-4
TAB Books

Contains a Hughes 500 Flight Manual

Learning to Fly Helicopters
R. Randall Padfield
1992, 0-8306-2113-X
TAB Practical Flying Series

Student Guide to Helicopter Flight Maneuvers
Sherry Knight Rossiter
1984
Progressive Pilot Seminars

Instructor's Guide to Helicopter Flight Maneuvers
Sherry Knight Rossiter
1984
Progressive Pilot Seminars

Basic Helicopter Handbook (AC 61-13B)
Federal Aviation Administration
Revised 1978

Aeronautical Decision Making for Helicopter Pilots
R.J. Adams and J.L. Thompson
FAA

Rotary Wing Flight
(Reprint of parts of U. S. Army FM 1-51)
Aviation Supplies and Academics, Inc (ASA)

Rotary Wing Flight: TM 1-260
Department of the Army
May 1965

Private Pilot Helicopter Rating
Charles Zweng
1965
Pan American Navigation Service

The Helicopter Pilot's Manual
Norman Bailey
1992
1-85310-188-5
Airlife Publishing Ltd

AERODYNAMICS

Helicopter Aerodynamics
R. W. Prouty
1985
Philips Publishing, Inc.

More Helicopter Aerodynamics
R. W. Prouty
1988
PJS Publications, Inc.

Even More Helicopter Aerodynamics
R. W. Prouty
1993
Philips Business Information, Inc.

Principles of Helicopter Flight
W. J. Wagtendonk
1996
1-56027-217-1
Aviation Supplies and Academics, Inc (ASA)

Principles of Helicopter Flight
Jean-Pierre Harrison
1993
0-9638491-0-7
Pilot Training Publications Co

Dynamics of Helicopter Flight
George H. Saunders
1975
0-471-75509-5
Wiley

Helicopter Theory
Wayne Johnson
1980
0-486-68230-7
Dover Publications

The Foundations of Helicopter Flight
Simon Newman
1994
0-470-23394-X
Halsted Press (Wiley and Sons)

Rotary-Wing Aerodynamics
W.Z. Stepniewski
C.N. Keys
1984
0-486-64647-5
Dover

Aerodynamics of the Helicopter
Alfred Gessow
1952 (8th printing 1985)
0-8044-4275-4
Fredrick Ungar Publishing

MAINTENANCE

Helicopter Maintenance
Joe Schafer
1980
0-89100-281-2
Jeppesen-Sanderson Training Products

MILITARY

Chickenhawk
Robert Mason
1983, 0-670-21582-1
Viking Press

Arguably the best written first-person account of helicopter warfare in Vietnam.

Choppers: The Heroic Birth of Helicopter Warfare
J.D. Coleman
1988
0-312-96635-0
St. Martin's Paperbacks

Hunter-Killer Squadron: Aero-Weapons, Aero-Scouts, Aero-Rifles, Vietnam 1965-1972
Matthew Brennan, Editor
1990, 0-671-74453-4
Pocket Books

Flying the Edge: In the Cockpit with Navy Test Pilots
George C. Wilson
1992, 0-671-87926-X
Pocket Books

Helicopters in Combat: The First Fifty Years
John Everett-Heath
1992
185409-066-8
Arms and Armour Press

Military Helicopters
E.J. Everett-Heath, G.M. Moss, A.W. Mowat, and K.E. Reid
1990
0-08-036716-X
Brassey's

Military Helicopters
Hugh W. Cowin
1984
0-8317-4200-3
Gallery Books

HELICOPTERS IN OPERATION

The Helicopter
Keith Carey
1986, 0-8306-2410-4
TAB Books

Pictures and narrative of numerous military and some civilian helicopters.
Not useful for pilot training.

Lift
Joe Stein
1985, 0-9614498-0-2
The Zig Zag Papers

Mostly narrative of the various uses of helicopters. It includes a great picture of a Boeing Vertol 107 pulling a hover barge, with the helicopter in what looks like a 60 degree nose-down attitude (the text indicates the helo got down as far as 35 degrees).
A color image of that picture can be seen here.

Hunting Lost Mines by Helicopter
Erle Stanley Gardner
1965
William Morrow and Company

Helicopter Pilot Reports
Aviation Week & Space Technology
1995
0-07-003168-1
McGraw-Hill

Covers a variety of military and civilian helicopters, including the Robinson R-44, Hughes 500D, MD Explorer, CH-47D, Apache, and others.

The Ten Second Jailbreak
Eliot Asinof
1973
0-03-001011-X
Holt, Rineholt and Winston

Slow going until our hero, the Bell 47, rescues an inmate held in a Mexican prison.

MISCELLANEOUS

The Complete Guide to Homebuilt Rotorcraft
Kas Thomas and Jack Lambie
1982, 0-8306-2335-3
TAB Books