Those of you who read my missives know how much I like Google, but I have found something that might provide some more relevant and limited results. It is called Blekko and the way it works is with use of slash tags. Those are those words preceded by a slash / to narrow your results. Many of us never get past the first few pages of results, so the limited pages is not an issue, and it does a fairly good job of filtering out spam pages. Super for searching business information.
If you want to search for pneumonia, and follow it with /health, you wind up with only 200 or so sites, but they are relevant sites. Each result also has a 'spam' button, so you can click the button to forever ban that site from your results. There is a few minute demo on the upper left side of the screen. It is in beta, but working now. Not completely ready for prime time, but getting close. Very cool stuff. LINK