Carrot2 is an open source framework for building search clustering engines.
meX Search is an application of Carrot2. meX provides a new look and feel of search engines.
Compared to traditional search engines, meX is visualized. meX starts from a search box as usual. However, results are categorized and presented to users as a graph, bubbles connected to the starting search box. Each bubble, representing one category, may contain one or more results with hyper links. Once a category is clicked, a new search start with the name of the category as the keyword.
meX takes Flash as a way for presenting the results, which means that a plugin is necessary. It should not be a problem (except that you are a member of ...) as flash is widely used on Internet. By the way, Wallop is another good example of flash applications.