How to use google search effectively?

What are the features of Google search?
How to improve the google search experience?

We always use Google search for almost all of our online search requirements. But do we know how to use google search most effectively? Do we know how to optimize our search query?

Here are few tips to increase your search experience?
1. For weather: type "weather [placename]"
2. For StockQuote: type the stock code
3. For Current Time: time [placename]
4. For calculation: type your equation left hand side, eg: 5*9+(sqrt 10)^3=
5. Unit Conversion: eg: 10.5 cm in inches
6. Dictionary Definitions: Type "Define [word]" eg: Define philosophy
7. Money conversions: eg: 150 GBP in USD

Reference: http://www.google.com/intl/en/help/features.html