Before we talk about which SE's matter to your search engine marketing efforts - it would help to read Search Engine Listing - What Are Your Options?.
You've probably heard all the rubbish about submitting your site to thousands of search engines...blah, blah, blah...
The people telling you that may have neglected to mention one tiny detail...
There are only about 100 search engines that get any amount of traffic.
Of the 100 that do - only 11 engines and 3 directories get a significant enough share of that traffic to be worth submitting your pages to at all.
To see which ones - take a look at my Free Search Engine Registration Guide. ( Clicking on this link will open a new window - simply close that window to return here ).
The break-down of the market share for each major SE or Directory looks something like this;
* Google - 29.5%
* Yahoo - 28.9%
* MSN - 27.6%
* AOL - 18.4%
* AskJeeves - 9.9%
* Overture - 4.8%
* NetScape - 4.4%
* AltaVista - 4.0%
* Lycos - 2.4%
* EarthLink - 2.0%
* LookSmart - 1.7%
Worth noting, is the fact that the Open Directory has lost it's market share of searchers to the point that it didn't make the cut ( less than 1% ) which means that there are really only two directories left, Yahoo and Looksmart, with any significant amount of traffic.
And if you look at the huge gap between the market share each of those directories hold it will be immediately obvious that Yahoo is truly where it's at when it comes to search engine placement.
Don't let any of the less ethical search engine marketers fool you - get your pages ranked at the top of the engines listed above and you won't need to worry about any of the others.
Search engine registration should be performed manually so knowing where to concentrate your efforts is very important and will save you time in the long run.
Now that you have great rankings - you'd probably like to know which of the figures provided in your Web Stats should you be looking at. Find out how to work that out by reading Targeted Web Site Traffic - Calculating ROI ( Return On Investment ).
http://www.seoplus.com/search-engine-registration.html