isimo is an excellent metasearch engine that also provides access to a number of large, authoritative specialized search engines. Altogether, it's a superb research tool.
Vivisimo (which is trying to sell its product to corporate customers) calls itself a clustering engine rather than a search engine because it organizes the results of other engines into groups or clusters. It seems to be designed to make finding information as convenient as possible for the searcher. Using Vivisimo, you can approach a subject from several orientations, refine your search, and visit sites with a minimum of time and effort.
In addition to accessing 12 web search engines, Vivisimo searches definitive search engines in the fields of health (Medline (or PubMed)), business (Business.com), government (FirstGov), patents (Delphion), news (CNN, World News, others), shopping (Yahoo!Shopping) and auctions (Yahoo!Auctions and eBay).
A RESEARCH POWERHOUSE
Vivisimo is useful for many types of research, but because of its particular combination of general search engines and specialized engines, it's ideal for any type of health-related research. For example, suppose you wanted to find information about the safety and effectiveness of influenza vaccines, new vaccine patents, and news and business developments having to do with vaccines.
You might start your query in Vivisimo by typing influenza vaccine or flu vaccination in the search box and doing a web search. Then, you might choose to search the specialized search engines relevant to your subject by selecting a category in the drop-down menu next to the search box.
If you elected to search Medline (or PubMed), Patents, and News, you would retrieve abstracts of articles from the leading medical journals, abstracts of the latest patents and current news articles
You might refine your search by adding such words (depending on their relevance to the engine you're searching) as safety, effectiveness, delivery systems, demand, etc. to your query.
SEARCH TIPS
You can use the plus and minus signs to require or forbid a word, in addition to the Boolean search operators AND, OR and NOT and NEAR. In my experience, quotation marks to signify a phrase also work although Vivisimo's Search Syntax Page does not include them.
It's advisable to go the search engines you're not familiar with to see which search operators they accept because Vivisimo will only submit your search to the engines that support the operators you enter. (For example, Medline (or PubMed) uses Boolean operators, while FirstGov does not).
http://www.suite101.com/article.cfm/search_engines/78816
