This article is from the alt.usage.english FAQ, by Mark Israel email@example.com with numerous contributions by others.
There are many such.
Of the two most prominent, one ("The National Grammar Hotline")
is run by Michael Strumpf, Professor of English at Moorpark
Community College, Moorpark, California, and author of "Painless,
Perfect Grammar: Tips from the Grammar Hotline" (Monarch, 1985,
ISBN 0-671-52782-7). The phone number is (805) 378-1494; the hours
are irregular, but he will return calls.
The other ("The Write Line") is run by Richard Francis Tracz,
Chairman of the English Department at Oakton Community College in
Des Plaines, Illinois, and author of "Dr. Grammar's Writes from
Wrongs: A supremely authoritative guide to the common and not-so-
common rules of the English language" (Vintage, 1991, ISBN
0-679-72715-9). The phone number is (708) 635-1948, and the hours
are 10:00 a.m. to 2:00 p.m. Central Time while classes are in
session. His e-mail address is "firstname.lastname@example.org".
In general, Prof. Strumpf gives more conservative advice than
For a "grammar hotline directory" that lists services state by
state across the U.S., see: