That is the fundamental law of economicis, competition brings better products to the market.
1. "Site Explorer allows you to explore all the web pages indexed by Yahoo! Search".
Great.
2. My Sites: "Track, Probe, Manage your site & feeds in Yahoo!"
Great too.
Together with
Yahoo search builder that allows you to add web search (and hopefully better) site search to your site.
Example: "Enhance the search engine algorithm to focus on your site's topic."
Enhance the algorithm should mean make it seamless fit the content of your site.