⌘ + C - Copy a text to clipboard
⌘ + V - Paste a text copied to clipboard
⌘ + Q - Closes any open application
⌘ + N | ⌘ + Shift + N - Open a new window for current application
⌘ + , - Access Preferences menu on any application
⌘ + Shift + ? - Access help menu on any application
⌘ + H - Hide all open windows for any application
⌘ + ⌥ + H - Hide all open windows application, except the focused
⌘ + Tab - Change between open applications
⌘ + ` - Change between windows for the same application
⌘ + P - open the print menu
⌘ + ↑ - Page Up
⌘ + ↓ - Page Down
⌘ + Space - Open Spotlight to make some search
⌘ + Mouse Drag - To move a selected file from a folder (volume) to another (keep ⌘ selected)
⌥ + Mouse Drag - To copy a selected file from a folder (volume) to another (keep ⌥ selected)
⌘ + I - To see and add information about selected file
⌘ + O - To execute a selected file
⌘ + E - unmount a .dmg image
⌘ + Shift + U - to access Utilities folder
⌘ + ⌥ + ⌫ - move selected file to trash
Space - open a preview window of the selected file
Enter - To rename a selected file
Ctrl + Mouse Rolled - Zoom in / Zoom out
⌥ + c - cedilha
⌥ + e - agudo
⌥ + ` - grave
⌥ + n - til
⌘ + Shift + 3 - take a full screen image (save as .png on Desktop)
⌘ + Ctrl + Shift + 3 - take a screenshot and copy to clipboard to be pasted anywhere with ⌘ + V
⌘ + Shift + 4 - enable mouse cross cursor to let you make a screenshot from a selected area (used with space to make a screenshot of an entire window)
⌘ + Ctrl + Shift + 4 - work as ⌘ + Shift + 4, except it copy the selected area to clipboard (to be pasted anywhere you want)
⌘ + ⌥ + ⎋ (Command + Option + Esc) - open an window with all running applications to select and force an application to close
⌘ + Shift + Q - logout from current session
⌘ + ⌥ + Eejct - put the system on standby
⌘ + Shift + Eject - shut down the display
F9[^1] - Mission Control
F10[^1] - Applications Window
F11[^1] - Desktop
F12[^1] - Dashboard
[^1]Those configuration can be customized on System Preferences > Mission Control > Keyboard and Mouse shortcuts
⌥ + ⌫ - erase an entire word to the left from where your cursor is
⌘ + ⌫ - erase an entire word on the current line
⌘ + ← - go to the beginning of the current line
⌘ + → - go to the end of current line
⌥ + ← - navigate words to left
⌥ + → - navigate words to right
⌘ + + - Increase font size
⌘ + - - Decrease font size
⌘ - R | ⌥ - during initialization, to access recovery HD