Merriam Webster's Dictionary on the Net http://www.m-w.com/netdict.htm
Wild card searches: if you recall how to spell only the beginning of carabiner (an oblong, hinged metal ring used in climbing), you can enter carab* and choose carabiner from the list of words that begin with cara.
Roget's Thesaurus of English Words and Phrases on the Web http://www.thesaurus.com/
A wonderful tool site offering hypertextual searches of the famed thesaurus.
The Use of Clichés http://www.nexus.edu.au/teachstud/dexed/docs/cliche.html
The account of an English teacher named Ms. English with an ax to grind who told her students to avoid clichés like the plague, this piece by Graeden Horsell says that sometimes clichés are needed, and that one should never say "never."
Language Policy Web Site and Emporium http://ourworld.compuserve.com/homepages/JWCRAWFORD/home.htm
Links to articles and Web sites on many language policy issues, including the English Only movement, bilingual education, Ebonics, endangered languages, and language rights.
African American English http://www.cal.org/ebonics/
The Center for Applied Linguistics sponsors this page about African American vernacular English; it includes many useful links.
Nonsexist Language http://www.stetson.edu/~history/nongenderlang.html
An essay exploring the origins of the practice of assigning masculine pronouns in gender-neutral or gender-inclusive situations and offering alternatives to the practice.