Yahoo manages their page rankings very different from Google. They appear to use the meta description on sites to search for relevancy. That’s an easier way to market your site, but I doubt that it provides for very honest and reliable information. They also take into account the information listed on the page that is indexed. They also appear to examine robot.txt’s to gather data. Yahoo and Google are really the biggies to worry about since they’ve bought up most of the smaller engines. It makes web designing interesting that’s for certain!