Ranks sites partly by subject-specific popularity. Clusters results into subject groups, and lists related link collections by experts and enthusiasts where appropriate. http://www.teoma.com/
Owned by Looksmart. Search results are clustered into categories. Preferences settings include search by language and a filter to remove adult content. http://www.wisenut.com/
A search engine with a clean interface, advanced search options including sorting by date, and a real time url submission feature. Includes PDF documents in its index. http://www.gigablast.com/
Powered by Nutch, it searches content which can be re-used (for somes uses) without having to pay or ask permission. http://search.creativecommons.org/
A cross between a search engine and an encyclopedia. The results return complete, informative sentences about the search topic. Related topics are suggested. http://www.factbites.com