I remember hearing the "Google-fu" expression forever ago on the Coding Horror blog. While my Google-fu may be a little stale, here goes what I use quite often.

123 * 45

Can be quicker than your firing up the calculator and typing it there.

1 usd to brl

The graph displayed along is quite nice.

translate cadeira

No need to navigate to translate.google.com just for that.

no silver bullet filetype:pdf

Watch out because pdf files can be dangerous. Always double-check the URL.

no silver bullet site:news.ycombinator.com

"why * is my favorite programming language"

Quotations and asterisk goes together just like... oh well.

DuckDuckGo-fu

I've used DDG for quite a while in the past and I remember fondly how smart some of its replies can be:

shorten wikipedia.org
wikipedia.org down
qr wikipedia.org
password
password 20
weak password
strong password
json beautifier
url encode açaí
calendar 1 jan 1999
lorem ipsum
html chars
ascii table