Dogpile (Meta Search Engine)

Dogpile is a meta search engine; it gets results 
from multiple search engines and directories and then 
combines them and presents to the user.

Dogpile page provides code to add search tool to your website.

It chases down the best results from Internet's top 
search engines, including Google, Yahoo! Search, MSN,
Ask Jeeves, About, MIVA, LookSmart and others.