Yahoo is where the cool things happen. Google is more structured and better in getting attention for new (beta) productlaunches, but Yahoo is knitting all their applications together into this incredible grid of everything.
For example take Yahoo suggestions a service where they talk to the user. They have a site explorer for tracking incoming links to your website. They know your favourite television programs. They even program your Tivo. They cluster pages with information from Flickr, etc. and they intend to do this at least a hundred times more. Yahoo has almost everything except order out of chaos.