Important note : I am using ReSharper 2.x / IDEA keyboard mapping.
Alt-Enter 
Whenever you navigate your code and see a bulb shaped icon at the left side of your code, hit the Alt-Enter key combination that will provide you with a set of actions you can do on the selected code block.
Alt-R/R
Open the refactor menu. This will present you with a list of possible refactoring you can do. This is the easiest way to start learning every refactoring's shortcut.
Ctrl-N
Find a class by it's type name. You can quickly navigate without the mouse to get you anywhere you want within your solution. This one will quickly become one of your most used shortcut.
Ctrl-Shift-G
At first you will need to know this one, but, when you'll become a ReSharper Jedi, you will forget everything about it's existence. Place your keyboard cursor on anything and hit those keys. You will then be able to move to it's declaration, inheritors, usages, unit tests, etc.
Alt-Insert
When you are navigating your solution (Ctrl-Alt-L), press the Alt-Insert key combination and you can create new folders, add classes an even add a file that you previously created with the template editor of ReSharper.