Isaac Asimov is the only author to have a book published in every major Dewey Decimal category.
Has he really covered them all?
Yes, I’ve heard that. He made a point of it, I think - once he realized he was close, he finished off the unaddressed categories.
http://the-tech.mit.edu/V112/N18/asimov.18w.html
Although he could not lay claim to publishing the largest number of books (the Guinness Book of Records identifies that champion as Josef Ignacy Kraszewski, a Polish writer of the 19th century who produced more than 600 volumes), Asimov did cover the largest range of subjects. He managed over his creative lifetime to have at least one book included in each of the Dewey Decimal System’s 10 major library classifications.
http://www.sfsite.com/isfdb-bin/exact_author.cgi?Isaac_Asimov
This site has a comprehensive listing of what he has written though it doesn’t list his works by their placement within the Dewey decimal system.
Hi! A friend of mine e-mailed me this discussion thread since I work in a library, and since my Mom is a Reference Librarian. What better source, right??? I forwarded her the question, and here is her response:
"Yes, I have heard this before. I just did some scouting, and found that he wrote books on these topics or with these specific titles:
000 – aliens, extraterrestrials, ufo’s
100 – psychology, The Human Brain
200 – Asimov’s Guide to the Bible
300 – Pollution in Space 363, The March of the Millennia
400 – Words From the Myths
500 – many science topics & titles
600 – many books on human body
700 – Asimov’s Guide to Gilbert & Sullivan, Fantasy Art Techniques
800 – Asimov’s Guide to Shakespeare, limericks
900 – history of US, Greece, Rome, autobiography
Never ask a Reference Librarian a question if you don’t want an answer!
Mom"
Aren’t Moms great? 
Welcome to the SDMB, Matt!
A fellow puddletowner, with a Reference Librarian in the family? Cool!