Google

Specifications

Features
Advanced search options?: Yes
Link to advanced search on start page?: Yes
Search inside books?: Yes, at Google Books
Note-taking built in?: SearchWiki; (Google Notes apparently no longer open to new users
Direct answers to factual questions?: Yes, sometimes
Search inside usenet groups?: Yes, usenet archives
Other notable features: Google Scholar
Tool bar available?: Yes, for IE and Firefox
Mobile version available?: Yes