Internet Utility - "Live" Dictionary/Thesaurus For Web Pages

Here's an interesting twist: Go to www.voycabulary.com and you can link any web page you want to a live dictionary and a thesaurus, allowing you to click on any word on your requested web page and get both a dictionary definition as well as a thesaurus suggestion for the word. Why would you need this? You may not, but it sure could be a useful teaching tool for your kids! Try it out and let us know what you think.