[Tfug] Blacklisting sites from Google results?

[Claude Rubinson]

I'm wondering if there's anyway to prevent Google from returning
certain sites in it's results.  There are a number of websites that
frequently show up in my search results that I find utterly useless.
(I'm specifically thinking of some of the linux-newbie forums but also
sites that simply copy Wikipedia's results, man pages, etc.)  Anyone
know if it's possible to prevent Google from returning certain sites?
Or, alternatively, hiding these sites from me (perhaps a GreaseMonkey
extension?).

Thoughts or ideas?

Claude