Easy to use and automatically maps your terms to standardized subject headings for optimal retrieval. Includes journals, CME, discussion groups, news. Encyclopaedia Britannica's Internet search directory. Keeps track of where you are within a hierarchy of subjects. Downloadable, free software allows you to search Britannica Online and other reference tools from your desktop.
Results vary, but a great place to try.
Uses several search engines, sorts retrieval in unique, but interesting categories. Still another meta-engine. Less elegant than others, but makes it easy to compare results between individual engines. After retrieval, eliminates duplicate hits and sorts results into often useful categories. Sorting makes large retrieval easier to cope with.