Do you know some good outline displayers?
Look at how Vivisimo (a new search engine) organizes results. It would be interesting to render OPML directories with a similar user interface.
05/21/01 update: I should mention QueryServer‘s result clustering.
06/08/01 update: look at SurfWax for another sites that organizes search results. Of course Northernlight started that a couple of years ago.
07/23/01 update: New IT company aims to increase speed of Internet, database searches.