You might start by reviewing the talks I gave on this topic at the Summer Institute on Technology in Teaching, and for the History and Technology Institute.
New Search Engines
• Google (www.google.com)
"This search engine distinguishes itself from other large engines through its extensive use of quality ranking. "Quality" is calculated from link popularity, anchor text references and text style" (http://www.teleport.com/~lensman/roadless.htm). Google also somehow keeps its sought results in a cache file, which means that you can retrieve older results even if the page in question has been updated in such a way that the information you require is no longer available.
• All the Web (www.alltheweb.com)
This is my current default search engine, in part because it is so fast and seemingly comprehensive. The FAQ for "Alltheweb" notes that "According to the latest NEC article in Nature, the World Wide Web by mid 1999 contains about 800 million documents, but in our experience with the FAST Web Crawler [AKA Alltheweb], 40% of these are duplicates. None of the big Web search engine have [sic] so far been able to make more than 160 million documents searchable. In May 1999, FAST announced with Dell a catalogue size of 80 million documents. [On] August 2, 1999, more than 200 million documents were made searchable, and it will hereafter continue to grow with the Web to 1 billion documents and beyond. Thus, with FAST Web Search you will be able to search All the Web, All the Time."
• InferenceFind (www.infind.com)
I find this to be the best search engine to model the search process for students in a computer classroom (with your results projected on the screen behind you) for it presents more than ten "discoveries" on a screen and organizes the findings in sometimes useful categories, such as commercial and educational sites. Here’s how the search engine presents itself: "InferenceFind is the first and only search tool that calls out in parallel all the best search engines on the internet, merges the results, removes redundancies, and clusters the results into neat understandable groupings. Inference Find queries the best 6 search engines on the web, but can be configured to call any search engine. Currently [InferenceFind uses] WebCrawler, Yahoo, Lycos, Alta Vista, InfoSeek, and Excite."
One of the best "bibliographies" on search engines and their use can be found at http://web.hamline.edu/administration/libraries/search/comparisons.html. It offers about 20 articles with titles such as "Beyond Surfing: Tools and Techniques for Searching the Web," "How to Search the Web - A Guide to Search Tools," and "Search the Net: Top Internet Searching Resources Reviewed." Many of these articles discuss search concepts such as case sensitivity, using phrases, required terms, prohibited terms, and wildcards.