Here's an online dictionary and thesaurus with a twist. Visuwords provides a web-like structure to show students the many connections words have that are sometimes missed in a classic dictionary format. All they have to do is type a word into the search field. The result is a web-like structure with the word in the center and nodes generated from the word. Each node will have a different connection to the word with visual cues in the key on the left hand side to show how the connection is related, whether it's showing similarities, parts of speech, derivations, etc. Hover the mouse over a node, and a definition will appear.
This site is probably best suited for intermediate grades because it is completely text based. Most of these students will probably be able to manipulate the graphics with ease and discover connections on their own as they "play". Try this new, more visual way to look at the words we use.