One of the great advantages of Ubuntu (and Linux in general) is the ability to customize your environment to your heart’s liking. Scrot is one such utility which really helps in accomplishing this in a remarkable way. The following command (when bound by a key) will take a screenshot, name the file with the day, date, etc and finally move it to the desktop.
scrot '%Y-%m-%d-%H-%M-%s.png' -e 'mv $f ~/Desktop'
