Webster's New Collegiate Dictionary, (1959)
The Elements of Style, (Strunk/White)
Amo, Amas, Amat and More, (Ehrlich)
Anasazi Ruins of the Southwest in Color, (Ferguson and Rohn)
Taber's Medical Dictionary
The Merck Manual
and my favorite:

The Little, Brown Book of Anecdotes, (Fadiman)