1)   Search Engine Explorer 4.1
Search engine explorer is a multiple search engine search tool. It allows up to 20 search engines to be running and searched simultaneously. The gruelling task of having to switch between search engines can be completely eliminated.

 2)   iMetaSearch 5.00
Search engines can't group results based on meaning, but iMetaSearch can. iMetaSearch groups search results by concept; click the groups that interest you and the search results will be revised accordingly. This is a powerful way to refine searches.