Keyboard Shortcuts for Ubuntu

General

Ctrl+A = Select all (In Documents, Firefox, Nautilus, etc, not Terminal) 
Ctrl+C = Copy (In Documents, Firefox, Nautilus, etc, not Terminal) 
Ctrl+V = Paste (In Documents, Firefox, Nautilus, etc, not Terminal) 


Ctrl+N = New (Create a new document, not in terminal)
Ctrl+O = Open (Open a document, not in terminal)
Ctrl+S = Save (Save the current document, not in terminal)
Ctrl+P = Print (Print the current document, not in terminal)

Ctrl+E = Send To...(Send the current document to an email recipient or remote location, not in terminal)
Ctrl+W = Close (Close the current document, not in terminal)
Ctrl+Q = Quit (Quit the application, not in terminal)

Ctrl + Alt + F1 = Switch to the first virtual terminal
Ctrl + Alt + F2(F3)(F4)(F5)(F6) = Select the different virtual terminals 
Ctrl + Alt + F7 = Switch to current terminal session with X

Ctrl+Alt++ = Switch to next X resolution (Depends of your X configuration)
Ctrl+Alt+- = Switch to previous X resolution (Depends of your X configuration)

Ctrl + Alt + Backspace = Kill X server

Alt+Tab = Switch between open programs
Printscrn = Print screen


Command line / Terminal shortcuts

Ctrl+C = Kill process (Kill the current process in terminal, also used to copy elsewhere)
Ctrl+Z = Send process to background
Ctrl+D = Log out from the current terminal. In X, this may log you out after a shuting down the emulator.

Ctrl+A = Home (Move cursor to beginning of line)
Ctrl+E = End (Move cursor to end of line)
Tab = List available commands from typed letters (Ex: type iw and click tab, output = iwconfig iwevent iwgetid iwlist iwpriv iwspy)

Ctrl+U = Delete current line
Ctrl+K = Delete current line from cursor
Ctrl+W = Delete word before cursor in terminal (Terminal only, also used to close the current document elsewhere)

Arrows up and down = Browse command history
Ctrl+R = History search (Finds the last command matching the letters you type)

Shift+PageUp / PageDown = Scroll terminal output
Ctrl+L = Clears terminal output
Shift+insert = Paste


Misc

Mousewheel click or 3rd mouse button = Paste selected text (Select any text in any window and paste where you want. Terminal / Firefox / Gnome apps)