For Gmail users, here's the run down of advanced query operators you can do to become a Gmail Search Ninja:

http://support.google.com/mail/bin/answer.py?hl=en&answer=7190

... and if you're not using keyboard shortcuts, you need to turn on and use keyboard shortcuts to become a Gmail Productivity Ninja:

http://support.google.com/mail/bin/answer.py?hl=en&answer=6594
(vi editor users, like me, might find some of these familiar...)
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