Dowser

Dowser is a research tool for the web. It clusters results from major search engines, associates words that appear in previous searches, and keeps a local cache of all the results you click on in a searchable database.

It helps you keep track of what you find on the web.

Future versions will have 'shallow' crawling of websites you click and a peer-to-peer component. Here is a very good discussion about distributed web searching.

-- Enjoy!
Aristus