Each search engine seems to produce different results. Google, Bing, Yahoo.
I tried a quick search recently using all three. The goal of my search was Vorotinschtina, a small agricultural colony established in the 1830s, adjacent to the hamlet of Zaverezhye, about 12 miles southwest of Mogilev, Belarus.
53' 50" N 30'03" E
101 mi E of Minsk
Vorotinshtina [Yid], Vorotinschtina, Worotyńszczyzna [Pol], Vorotinschtina-Zaverezhye
53'50" N 30'03" E
101 mi E of Minsk
Zaverezh'ye [Rus], Zaverezhye
Results for each set of results pulled items from FamilyTreeDNA.com, JewishGen, blog posts from MyHeritage Genealogy Blog and Tracing the Tribe blog, YNetNews, Jerusalem Post.
Bing produced 14 results. and did not seem to pick up on many blog posts.
Google returned 102 hits, many were duplicates, leaving 28 "real" ones, and one in Spanish.
Yahoo offered 42.
As another simple test of all three, I decided to search for myself to see what numbers each would pick up. I used "schelly talalay dardashti" as the search parameter to limit it to myself and skip mentions of cousins in both families, etc.
Bing 4,520 (but could not click on results higher than 450).
Yahoo: 7,340, including Facebook
Closer to home, decided to see where and how MyHeritage.com's new Family Tree Builder 4 fared. Here are the results for "MyHeritage.com Family Tree Builder 4.0" -
Results for "MyHeritage.com" without FTB 4.0:
There are some other sites coming down the road, such as Yebul/Yabul and Kosmix.
In June 2009, tech blogger Phil Bradley's provided information on several sites that permits users to compare results from multiple search sites, which can be interesting as you compare site results side by side.
Blind Search http://blindsearch.fejus.com/.
Run a search and get a three-column set of results - simply choose the one set of results that you're happiest with. You'll then see the engines popped up afterwards; Bing, Google or Yahoo.
Bingandgoogle and Bingle do the same thing. The exception is that with Bingle you can switch the results to one search engine or the other.
Tripleme searches across Yahoo, Google and MSN Live, which seems to pull Bing results).
GrabAll allows you to compare two-pane results for Google, Yahoo, Ask, Bing, DMOZ, AltaVista, Gigablast and Looksmart.
Scour lets you check out results from Google, Yahoo and Bing.
Searchboth lets you compare results from Google, Yahoo, Ask, Dogpile, MetaCrawler, AltaVista, Looksmart and Websearch in a two-pane window.
Soovle is a different method, and provdes page access to Google, Wikipedia, Amazon, Answers, Yahoo, Bing and YouTube, Type in a keyword and Soovle comes up with alternative terms - click on any and your search will be run on the appropriate engine.
Awhile back, I checked out Yebol.com, but now it seems to have been suspended. Clicking on the URL brings you to a Bing page which says Yebol has been suspended.
Its mission according to a posting of a few months ago was "to build human-like world's knowledge base and provide knowledge based search (semantics) and services. Yebol allows for a multi-dimensional search result instead of the normal one-dimensional search seen by most web search engines today." With its suspension and no news about when it might be coming back, there wasn't a way to test it.
In any case, researchers need to check several search engines and also learn how to use each search engine to the best end result. There are many ways to find information, how to construct searches of search engines to find what you need. And always check several search engines.
I'm always interested in reading your comments.