http://www.quintura.com
It's like a cross between a mind map and a search engine. I've seen similar stuff before in the enterprise search market (by companies like Autonomy) but this is the first internet search engine I've seen that uses it. The proximity of the terms represents their closeness in terms of search matching if that makes sense - you can click on a secondary search e.g. click on roadster V8 researches using that term and remaps the results....
Try it below...
<div><script type="text/javascript" language="javascript" src="http://www.quintura.com/light_2.asp?Par ... ript></div>