WordSolverUK - WordSolverUK is a new PC program containing a word search (700,000 words for helping with spelling, crosswords etc.), an anagram solver and a thesaurus with over 1 million cross references and is written in English.
Bibliodata - Free to use online thesaurus that offers synonyms, example usage, derived forms and antonyms. Bibliodata also features helpful writer’s resources, a word of the day, quotes and interesting facts.
Lexigram - Free online thesaurus and dictionary containing 1,600,000 related words and phrases and 125,000 root words.