examples from:
http://www.google.com/support/websearch/bin/answer.py?hl=en&answer=136861

Try natural language searching first-- Google is optimized for this.

Use CAPS when entering Boolean terms.

Use parentheses to organize multiple search strategies, ie: (teach OR train OR training) "online searching" tutorials site:edu

AND is not necessary. It's implied. ie: cats dogs = cats AND dogs in a Google search.

OR tells Google to search for either one of several words, for example [ San Francisco Giants 2004 OR 2005 ].

" " (double quotes) around a set of words tells Google to consider the exact words in that exact order. Google already does this for the most part, and by doing this you may be missing good results. For example,a search for [ "Alexander Bell" ] (with quotes) will miss the pages that refer to Alexander G. Bell.

site: allows you to search within a site. For example: [ iraq site:nytimes.com ] or [ iraq site:.gov ]
One way to find more reliable sources is to limit by the following domains with the site limiter:

• .gov
• .edu
• .org
• .mil

- allows you to exclude certain terms. The minus sign should be before the word you want to exclude and should be preceded by a space. In the example [ anti-virus -software ] Google reads "anti-virus" with a hyphen, but "software" as a word to exclude.

+ ensures that a word is in your search, and that synonyms are not automatically searched (which they are by default).

* acts as a placeholder for unknown terms. This works in whole words, but not parts of words. For example, [ Obama voted * on the * bill ] will give results on different votes on different bills.