D is for dictionary
Oxford English Dictionary (OED): "It is an unsurpassed guide to the meaning, history, and pronunciation of over half a million words, both present and past. It traces the usage of words through 2.5 million quotations from a wide range of international English language sources, from classic literature and specialist periodicals to film scripts and cookery books." The OED site includes the word of the day by e-mail and how to contribute to the OED.
T is for
Turns of Phrase
"words that are relatively new and which often have not yet reached the dictionaries"
U is for
Universal Language of Color
"Armed with the standardized language of color, the researchers at the National Bureau of Standards reviewed a number of color atlases and mapped their names onto the centroids. The result is a fascinating dictionary of color terms. Ever wondered exactly what color London Fog was? Celestial yellow? Rembrandt's Madder?"
V is for Visual Thesaurus
"The Visual Thesaurus takes a unique, and remarkably beautiful, approach to presenting the results of a word lookup. Discover and learn from nearly 140,000 words, meanings and relationships." (site)
"Inventive. Imaginative. Ingenious. Fanciful." (The New York Times)
W is for Word Spy
"This Web site is devoted to lexpionage, the sleuthing of new words and phrases."
X is for Xlation.com
1683 glossaries in several languages
Y is for
dictionaries, glossaries, courses, gameroom, endangered languages and more