Boolean searching is with buttons or symbols. MetaCrawler's power search allows narrowing by geographical location or educational, governmental or commercial sites. MetaCrawler has an interesting feature called Metaspy . Profusion claims to be able to analyze your search terms and pick the best three search engines . Filters results to remove duplicates and broken links.
Profusion has good Boolean searching capabilities.
One of the unique features of Profusion is the Personal Assistant . Dogpile, Inference Find, MetaCrawler, and Metafind.