The Joy of Exclusionary Keywords

I left a comment over at 0xDE (anonymous, I couldn't figure out how to get the attribution to work). The basic problem discussed in his post is the declining usefulness of Google due to the burgeoning number of sites selling stuff. More and more, it seems every search is returning a sales pitch.

Searching for me is becoming a fine art. There are right ways and wrong ways to do it. For example, if you do an unqualified search for X and cancer, naturally, you're going to find the web page of some yahoo claiming X causes cancer.

When I search for most information, a good proportion of which amounts to professional research, I tend to append "site:.edu" to Google searches which restricts the search primarily to colleges and universities. Unfortunately, great institutions such as Cambridge, Oxford (ac.uk sites) don't make the cut. I may just create a special search page to fix this problem.

My comment over at 0xDE, however, notes the joy of using exclusionary search terms. If you prepend a minus sign to a term, it will be excluded from the search. I suggested using -price or -order since most sites selling things want money (although, in retrospect, order is a pretty general term).

Therein lies the challenge of the day...

What's the best exclusionary Google keyword to generally filter out peddlers?