I went back through all of the shortcuts that I could find and tried them on Ubuntu 9.04. Interesting that some of them did not work so I left those out. All of these shortcuts should work on a default Ubuntu installation.
Basic Keyboard Shortcuts
When you consider using keyboard shortcuts always think about the Ctrl key as that is the first key you will use with all of the keyboard basics.
Ctrl + C = Copy the highlighted content to clipboard
Ctrl + V = Paste the clipboard content
Ctrl + N = New Create a new document (works with gedit, OpenOffice, not terminal)
Ctrl + O = Open a document
Ctrl + S = Save the current document
Ctrl + P = Print the current document by selecting a printer
Ctrl + W = Close the close document
Ctrl + Q = Quit the current application
Keyboard Shortcuts for GNOME Desktop
Ctrl + Alt + F1 = Switch to the first virtual terminal
Ctrl + Alt + F2(F3)(F4)(F5)(F6) = Select the different virtual terminals
Ctrl + Alt + F7 = Restore back to the current terminal session with X
Virtual terminals or ttys allow you to login as different users or multiple times. The virtual teminals F1-F6 are command line only, F7 is the XWindow.
Ctrl + Alt + Backspace = Restart GNOME
Alt + Tab = Switch between open programs
Ctrl + Alt + L = Lock the screen, this will require user password to open
Alt + F1 = opens the Applications menu
Alt + F2 = opens the Run Application dialog box
Alt + F4 = closes the current window which is highlighted
Alt + F5 = unmaximizes the current window
Alt + F7 = grab and move the current window
Alt + F8 = resizes the current window with mouse
Alt + F9 = minimizes the current window by placing on the panel
Alt + F10 = maximizes the current window
Alt + Space = opens the window menu on the currently highlighted application
Ctrl + Alt + Left/Right = move to the next/previous workspace
Keyboard Shortcuts for Terminal
Do not mistake these shortcuts with shortcuts for vi or any other editor that you may have open.
Ctrl + C = kills the current process.
Ctrl + Z = sends the current process to the background.
Ctrl + D = logs you out.
Ctrl + R = finds the last command matching the entered letters.
Enter letters which will be followed by Tab + Tab = lists the available commands beginning with those letters.
Keyboard Shortcuts for Nautilus
Shift + Ctrl + N = Create New Folder
Ctrl + T = Will add a tab to the window
Alt + ENTER = Show File/Folder Properties
Ctrl + 1 = Toggle View As Icons
Ctrl + 2 = Toggle View As List
Ctrl + S = Select Pattern by opening pattern window
F2 = Rename File
Ctrl + A = Select all files and folders
Ctrl + W = Close Window
Ctrl + Shift + W = Close All Nautilus Windows
Ctrl + R = Reload Nautilus Window
Alt + Up = Open parent directory
Alt + Left = Back
Alt + Right = Forward
Alt + Home = go to Home folder
Ctrl + L = go to location bar
F9 = Show sidepane
Ctrl + H = Show Hidden Files
Ctrl + + = Zoom In
Ctrl + – = Zoom Out
Ctrl + 0 = Normal Size
Are you looking for Ubuntu commands? Check out our Command Manual PDF.