"LinkRanks differs from competing ranking systems on a number of fronts. Relying on a nightly analysis of Web feeds, PubSub calculates which blogs are the most influential, which are getting the most number of links, and which links come from the most influential sites."
In other words, the site with the most links does not win in this search facility, as not all links are created equally. A link from an influential site, carries more weight than a link from a site no-one else links to. It's another tool for finding and listing blogs, and comes at it in a different way that can help you see things you might miss if your just using google etc.
You also might want to check out the main PubSub search facility. With this search engine, you create a search request, and it carries on looking for you, and notifies you when it has found something new. A search that carries on searching and can notify you via a sidebar in your browser or RSS feed when it has found something extra for you.