I was playing with Ubuntu last night writing a comparison between Unity and KDE when I came across a feature I was not aware of. Not that it is an extremely important feature but its the small stuff that matters.
If you are using a multi-monitor set-up on Ubuntu, the login screen does something interesting, the login window will appear or switch to the monitor where the mouse is. That's pretty neat if you are on a multi-monitor set-up. Check out the video below.










