The Boolify Project offers a very cool visual search engine so students can see the exact logic behind their search and how changing their search can change their results. Their search is put together like the pieces of a puzzle that they can easily add or remove one by one. Their search results are then placed at the bottom of the page.
They even have lessons to help use the site, and many new and awesome tools promised to come later this year. I am sure if they are as good as their Search Engine, I will be blogging about them as well.