Hi,

There are actually a few thousand different search engines out there depending on what you want to search for.

A big listing of the most popular 200 or so (?) are listed here: http://www.peopleferret.com/free-behemoth-search.htm. They aren't categorized, however there are specialized search engines for engineering, medical, research, children related and academic etc.

Using a specialized search engine sometimes works better since the data available is very specific to a particular area and there's either more information on it or more detailed information.

Sincerely,

Traveling Girl