Dictionaries

Dictionaries
Merriam-Webster dictionary and thesaurus on-line.
http://www.webster.com/

This site speaks for itself. Also has a thesaurus.
http://www.britannica.com/
A visual thesaurus
http://www.visualthesaurus.com/index.jsp
Another dictionary site
http://dictionary.reference.com/
Search in numerous dictionaries
http://www.onelook.com/
A biographical dictionary
http://www.s9.com/
Rhyming dictionary and thesaurus
http://www.rhymezone.com/