I've been using Ubuntu for about three years now and I've never taken the time to learn the keyboard shortcuts. I've wasted so much time taking the extra second to move my hand over to the mouse. The purpose of this article is to quickly teach you useful time-saving keyboard shortcuts available in Ubuntu.
I don't like wasting your time so let's get right to the point
CTRL+ALT+L
I try to do this when I leave my desk for any amount of time, which is multiple times throughout the day. The above key combination will display the screen saver and then require your password when you return.
CTRL+ALT+LEFT/RIGHT ARROW KEY
Very useful when switching between projects or tasks!
CTRL+ALT+D
To minimize all your applications and display your desktop try the above key combination. I don't user this very often but thought you might
ALT+TAB
This is the key combination I use the most! I use this one more at home then I do at work as at home I don't have dual monitors. If you work in web design you switch back and forth between a browser every few seconds. Not using this key combination would add minutes of time to your work every day and hours per month.
SHIFT+CTRL+ALT+LEFT/RIGHT KEY
This one is new to me and I've not used it much, now that I know it I'll try to put it to use. Please leave a comment of how you use it.
ALT+F9 (minimize) ALT+F10 (maximize) ALT+F10 (pressing again will restore to original size)
ALT+F2
Very handy, but I prefer the terminal
Ctrl+H
I remember this one from my windows days. I assume this is common through all operating systems. Comments Mac users?
Shift+Backspace
I use this quite often when I'm configuring displays
F2
F2 renames a file in Nautilus, this is common among most operating systems.
F5
The F5 key combination is probably the most widely know shortcut for web developers as it works in every Linux and Windows browser (not Mac, which is Command + R). F5 also works in Nautilus
I mentioned above I prefer to run a terminal over the run command. As far as I'm aware there is not already a shortcut for doing this (because of CTRL + ALT + F1-F6) so you can edit your preferences.
System > Preferences > Keyboard Shortcuts