Advanced Google operators

I know vyoma's got a big hate on for Google right now (and he has some valid points for this, too), but I still have a little crush on the company for all the useful shit it can do for us.

Here are some great examples. I always forget to use it as a calculator and conversion tool.
http://www.googleguide.com/advanced_operators_reference.html

Also, from Google itself, its cheat sheet:
http://www.google.com/help/cheatsheet.html