Checking Inbound Links
Links coming into your site are indexed differently between search engines. To get a quick read of this, you’ll need to plug a search limiter with your domain name into a search engine. For example, in Google you might search for “link:www.yourdomain.com,” while in Yahoo the same query would be “linkdomain:www.yourdomain.com.” Queries of this sort will return every page in the search engine’s index that links back to your site. The number to track is the total number of results returned by the query.
The difference between search engines is usually based on what they consider to be a valid inbound link. Google, for example, rarely considers any link from a page with a PageRank of less than 4 to be valid. Thus, inbound links in the Google index are very valuable. Yahoo, on the other hand, seems to index any page with a link to your site, regardless of quality or content. Therefore, inbound links in the Yahoo index are easy to come by.
The last consideration to take into account is the variability of these links. Yahoo and MSN can both vary drastically from week to week, while Google generally remains constant. Give this some thought when you see a change in the numbers. A change of even a few pages in Google can be very significant, while a change of hundreds or thousands of links may be commonplace in Yahoo.