Merriam-Webster
Online - on-line Dictionaries, a Thesaurus, Word Games, a Word of
the Day http://www.m-w.com/ (see OneLook:
Dictionary Search for a list of additional Dictionaries)
Voycabulary
- makes the words on any web page into links so that you can look
them up with just a click! http://www.voycabulary.com/
Wordsmyth
- Use the Wordsmyth toolbar button to look up any word on any web
page.
http://www.wordsmyth.net
Visual
Thesaurus - an interactive map showing the meaning of your word.
No longer free - $39.95 CD or $19.95/year online
version http://www.visualthesaurus.com/index.jsp
eBooks:
Project Gutenberg - online published books that are in the
public domain or with copyright holder's permission http://www.gutenberg.org/catalog/