Vivisimo Clustering – automatic categorization and meta-search software is a meta search engine with a great outliner like interface that lets you move through lots of hits. They gather hits from other engines and cluster them into a hierarchy that can be browsed. The idea is obvious once you try it for searches where you want to manage lots of hits. Thanks to Matt for this.
They have a toolbar, but for Windows. Pity.
They also have an Enterprise Publisher and Content Integrator that can organize your info or search across databases and so on.