Scirus is a useful science only search engine that searches over 415 million science-specific web pages for scholarly and technical data. The results are all science related information rather than general interest pages that are searched by other search tools like Google.

The benefits of using a specialty search engine for highly specialized searches include usefully limited types of information, predetermined filtering, and advanced indexing. From the Scirus about page:

Filters out non-scientific sites. For example, if you search on REM, Google finds the rock group - Scirus finds information on sleep, among other things.

Finds peer-reviewed articles such as PDF and PostScript files, which are often invisible to other search engines.

Searches the most comprehensive combination of web information, preprint servers, digital archives, repositories and patent and journal databases. Scirus goes deeper than the first two levels of a Web site, thereby revealing much more relevant information.

Scirus searches include publications indexed by Lexis-Nexis, NASA, and Science Direct among other sources.

Scirus was voted Best Specialty Search Engine' in 2001 and 2002 by the Search Engine Watch Awards.