I am a big fan of Hotkeys/shortcuts, here is a few I have collected, I will be adding more as I find them.
Several of the most popular keyboard shortcuts in Windows work in Ubuntu as well, such as Ctrl-C to copy, Ctrl-V to paste, and Ctrl-S to save a file. Here are a few others for working faster in Ubuntu and its apps:
Alt-Ctrl-L Locks the screen.
Alt-F1 opens the Applications menu, then use the arrow keys to navigate the submenus.
Alt-F2 opens the Run Application dialog box.
Alt-F3 opens the Deskbar Applet (F3 opens the search bar at the bottom of the window).
Alt-F4 closes the current window.
Alt-F5 unmaximizes the current window (if it's maximized, of course).
Alt-F7, followed by arrow keys or mouse movement, adjusts the current window's position.
Alt-F8 resizes the current window.
Alt-F9 minimizes the current window.
Alt-F10 maximizes the current window.
Alt-spacebar opens the window menu.
Alt-Tab moves between open windows.
Ctrl-Alt-Tab moves between open panels on the desktop.
Ctrl-W closes the current window.
Ctrl-Q closes the current application.
Here are some keyboard shortcuts for working in the Terminal window:
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.
Tab followed by entered letters lists the available commands beginning with those letters.
Ctrl-U deletes the current line.
Ctrl-K deletes from the cursor right.
Ctrl-W deletes the word before the cursor.
Ctrl-L clears the terminal output.
Shift-Insert pastes the contents of the clipboard.
Alt-F moves forward one word.
Alt-B moves backward one word.
If you know of any other Shortcuts, please feel free to post them in the comments!
Adjust your keyboard shortcuts: Ubuntu makes it easy to customize your shortcuts. Click System > Preferences > Keyboard Shortcuts, select one of the shortcuts in the list, and enter your preferred keystroke combination. You can also alter your keyboard accessibility options by clicking System > Preferences > Universal Access > Keyboard Accessibility. Here you can enable and adjust the timing for sticky keys, repeat keys, slow keys, bounce keys, toggle keys, and mouse keys (these convert your numeric keypad into mouse controls).