If you interest to lock desktop with interesting feature, you can try to use ClearLock. This program offers transparent layer, which allows you to see what is happening in your desktop without have to enter password or open the lock.
To run ClearLock, you just have to run it, set password and click the icon of the program anytime you want. This program is specially built to prevent others who will disturb or open your desktop. This program is also purposed to help secure your desktop from irresponsible people. Published by Swan River Computer, you can download this 957 kb below.