IntelliJIDEA shortcuts

• list of usages: Show usages is a very simple but powerful feature. Just press Alt + Ctrl + F7 (Alt + Cmd + F7 for Mac) 
• Paramter Info : The information on parameters required for a particular method is available via Ctrl + P (Cmd+P) shortcut.
• Show implementation: If you want to quickly look at the implementation of a symbol at the caret, you can call the Quick Definition by pressing
  Shift + Ctrl + I (Shift + Cmd + I).
• documentation : Ctrl + Q (Ctrl + J for Mac).
•  last accessed file:  The real time-saver here is action called Recent files via Ctrl + E (Cmd + E for Mac). 
• Methods : The shortest way to do it is to press Ctrl + F12 (Cmd + F12 for Mac) if you click again you see inhrerite members
• Navigate between methods : If you need to jump over the methods quickly just press Alt + ↑↓ 
• Navigate to Class, File and Symbol : This feature is available via Ctrl + N
• Navigate to file : Just like for classes it works for files as well, via Ctrl + Shift + N   
• Navigate to symbol : And finally the most tricky feature is to navigate to a symbol via Ctrl + Alt + Shift + N 
• Navigate to line number via Ctrl + G (Cmd + G for Mac)
• Navigate to declaration via Ctrl + B (Cmd + B for Mac)
• Navigate to super via Ctrl + U (Cmd + U for Mac)
• Navigate to implementations via Ctrl + Alt + B (Alt + Cmd + B for Mac)
• Navigate to the last edit location via Shift + Ctrl + Backspace (Shift + Cmd + Backspace for Mac)
• Navigate to the next error or warning via F2
• Navigate to a related unit test via Shift + Ctrl + T (Shift + Cmd + T for Mac)
• Basic completion  simply press Ctrl + Space shortcut. 
• Smart completion, press Shift + Ctrl + Space.
• Statement completion automatically adds missing parentheses, brackets, braces and adds the necessary formatting. To complete a statement, just press Shift + Ctrl + Enter
• Structural selection: A definite must-know to be even more productive. Structural selection allows you to select expressions based on grammar. By pressing Ctrl + W (Cmd + W for Mac) you keep expanding your selection (starting from the caret). And vice versa, you can shrink it by pressing Shift + Ctrl + W (Shift + Cmd + W for Mac).
• Move the current line of code (or selected block) via Shift + Ctrl + Arrows (Shift + Cmd + Arrows for Mac).
• Duplicate a line of code (or selected block) via Ctrl + D (Cmd + D for Mac)
• Remove a line of code (or selected block) via Ctrl + Y (Cmd + Y for Mac)
• Comment or uncomment a line of code (or selected block) via Ctrl + / (Cmd + / for Mac) and Shift + Ctrl + / (block comment for selected code).
• Optimize imports via Ctrl + O (Cmd + O for Mac).
• Find in the currently opened file via Alt + F3 (F3 to the next match rance and Shift + F3 to the previous match). Or, replace in the currently opened file via Ctrl + R (Cmd + R for Mac).
• Enable/show soft-wraps, disabled by default.
• Paste from stack via Shift + Ctrl + V (Shift + Cmd + V for Mac).
• Navigate between opened tabs via Alt + Arrows (Ctrl + Arrows for Mac).

This article is also very good about intellij idea : http://arhipov.blogspot.de/2011/06/whats-cool-in-intellijidea-part-i.html 

intellij for eclipse developers http://virgo47.wordpress.com/2011/04/10/from-intellij-idea-to-eclipse-4/

Source: http://confluence.jetbrains.com/display/IntelliJIDEA/User+Interface