I had a free weekend, and the thsrs idea by Ironic Sans [1] looked like something too cool to let it go (and http://thsrs.com/ didn't work too well for me). Also, it was a chance to implement my very own instant search ;-)
The thing is done in Django+PostgreSQL+jQueryUI and uses the Wordnet 2.0 thesaurus which comes with OpenOffice. My wife was kind enough to make it look not ugly.