A very interesting search engine I came across while searching for some health stuff, so during my research I came across Kosmix which was great to search.  It categorizes your search and also displays topic wise results.  I also just read that Kosmix announced that its patent-pending Kosmix Health Search technology will power a customized, health-only web search tool on The HealthCentral Network which is  the world's leading collection of consumer health web sites.