DowserDowser 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.

(Via The Tao of Mac.)

This is another interesting tool that runs locally on your computer. It basically catalogs your web searches on your local computer and creates a searchable local database of your searches. Now I can search my searches. Requires Python...