Visuwords is an interesting interactive visual thesaurus tool. Users can look up words to find their meanings and associations with other words and concepts. It produces an interactive node diagram which shows how the words are associated with other words.
Enter words into the search box to look them up or double-click a node to expand the tree. Click and drag the background to pan around and use the mouse wheel to zoom. Hover over nodes to see the definition and click and drag individual nodes to move them around to help clarify connections.
Take a look for yourself at : http://www.visuwords.com/