Via John Dowdell, a cheat sheet of google's Boolean operator protocol. Fairly standard but always good to have a cheat sheet. There's also a book called "Google Hacks" full of tools and tricks for power users (some of it was above my head technically, but there's still some good stuff in there)

Alta Vista used to have a good tutorial but it's long gone <sigh>...why do they get rid of the good stuff? (Yeah, and who was it that decided to cancel "My So Called Life" too?! I miss Angela Chase)

By the way, MSN let's you tweak how your results are returned, by file type, language, location, other stuff. I'm just saying.

And there are more guides online on Boolean and searching here, here, here, here,  and with ven diagrams here. If you want to search for more info on Boolean search strategies, use the word "advanced" as a keyword. Most of the info out there just gives you the basic operators.