Search Engines (SE's) play a very important role to most websites, overlooking this can cause you a lot of wasted time and money. First lets define the players.
Google
Google, the king of search engines, people will claim how other search engines are better but the stats for my sites don't lie. Google is dominating my referrals from my lowest at 42% to my highest at 73% of all visitors. "Content is king" when it comes to Google, the more content the better search listing* you will receive. The other major factors when it comes to google is the age of your site. Older more established sites rank better then fresh sites. In Bound Links (IBL's) is probably the most important single factor when it comes to ranking your site in Google.
*Assuming your site is properly optimized
Yahoo
Yahoo, nothing really sticks out with yahoo that defines them better then their users. Yahoo has a devote group of followers that use Yahoo and will probably continue to use Yahoo as long as they use the internet. Another oddity of Yahoo I've noticed is that it doesn't differentiate between singular and plural phrases. This can either be a good thing or a bad thing depending on your search phrase and website. Yahoo is the second largest referral of visitors to my sites, however over the years of tracking stats this percentage seems to be declining to MSN.
MSN
MSN, has one superior advantage to the other top search engines and that is speed. What I mean is the time it takes for a new page to be indexed and ranked in the major search engines. I can usually count on msn to rank a page quicker then the other SE's and this will be an early guideline to how the other search engines will rank the page. MSN is generally the third highest referral of visitors to my sites.
The Others
There are a multitude of other search engines out there and while they do lead visitors to my sites, this only accounts for a total of less then 3% of total visitors. Generally speaking not enough traffic to go into any specific details in any one of "the other" search engines.
