http://www.intelseek.com/
This one is kind of unique: http://mooter.com:8080/moot
I really like the clustering on Mooter! It gives a nice graphical representation of groupings on the web.
I agree, the clustering of keywords is good, but there are 2 bad things about this one that I read in another forum: 1) Speed 2) If you ask a question to it (query) it replies back with the question for clustering, now, Users just want results (all the popular search engine do that) users don't want to make decisions when they are searching the web, and I know many people that don't know what "Clustering" means, and in fact, when I first started using this engine, I was totally lost. If those 2 can somehow be fixed, this engine will run.
The clustering is probably of much more interest to "webmaster types" than to the average searcher who might find it confusing.
exactly