DEVONagent looks very promising
DEVON Technologies is getting ready to release DEVONagent, a flexible agent that searches the web for you.
Technically, DEVONagent is a fast and flexible agent finding information using our flexible DEVONtechnology. It uses a variety of searching techniques and collects the results. Then it visits all the found web sites, downloads, analyses and weights them to find the most relevant pages, eliminating information junk (empty pages, HTTP errors, sites that don't contain the search phrase, similar or duplicate pages, or pages with too little information) automatically on-the-fly. Of course, you may use boolean operators to narrow your search phrase.
Judging by the screenshots and descriptions, it looks very promising!