Yes, specialized dictionaries should count. I included "The Highly Selective Dictionary for the Extrordinarily Literate"--and a few other specialized ones.

But I didn't include tree, bird, and flower books for the hobbyist since it seemed to me the photographs were more to the point than the defining of terms.

I think if the book has primary emphasis on definition, then it would be good to include.

Edit:

Here's my list since the wind bloweth hard and I goeth not outside:

Riverside Webster's (1987)
American Heritage (1992)
American Heritage (at school; black cover; ABC's on cover?)
Random House Word Menu (great fun!)
Highly Selective Dict. for the Extraordinarily Literate
The Modern Physician (1942) ...also great fun!
Two copies of Anu's 'a word a day'
The Original Roger's Thesaurus (1965 edition)
Roget's College Thesaurus in Dictionary Form
Facts on File Visual Dictionary
Origins of Sea Terms (thank you, Dr. Bill)
Harvard Dictionary of Music
Oxford American Dictionary (Ha!)
Mrs. Byrne's Dictionary of Unusual, Obscure, and Preposterous Words (hello, tsuwm)
The Dictionary of Cultural Literacy
The New American Dictionary of Difficult Words (faze/phase and gang)
Meriam-Webster's Vocabulary Builder--highly recommended for students
Roget's II: The New Thesaurus (I like the original better)
1100 Words You Need To Know (You already know these, I'm sure)
QPB Encyclopedia of Word and Phrase Origins (really, it's a word reference)
The Compact Music Dictionary
Webster's Dictionary Unabridged (1857)
Webster's Ninth New Collegiate
The American Heritage Children's Dictionary (somewhat of a disappointment)
Two thesauruses at school, almost completely falling apart
...and the OED in the attic
That makes 28, but I'm just counting anu's as one.