I have never been a fan of yahoo because I never got much traffic from them. Here recently I have been purchasing a lot of keyword heavy domain names and my yahoo traffic has increased enough that now I value the searchers Yahoo sends my way. So this is what I've notice. Yahoo puts a lot more weight on domain names then google does. For example I have a
serpentine belt diagram site, which has ranked #1 for its kewords within two weeks of putting it up. Google has not been as friendly.