I see that ask.com is know using thesaurus concepts. Search for a term, and look at the left hand bar. It includes options to expand your search, narrow your search or view related names (i.e. terms). It shows best bets, with more links for further options. This application if information architecture concepts is a huge leap forward for usability. Of course, it raises questions about the quality of the data. Can it be created by machine? Is it the job of a librarian? How do we take advantage of social tagging? I hope this facility will get people thinking about the funcationality of their institutional web search.