Switch off Monitor in iMac
I were searching for an option to switch off my iMac monitor, whenever I am not using it. And there were lot of options provided, some thing goes like using a Utility and lot more. But I stumbled upon this site http://www.ehow.com/video_2179481_turn-off-imac-display.html where they had advised to use CTRL+SHIFT+EJECT to get them done. And really it worked. Cheers! Thanks for the person who suggested it.
Instruction to Follow:
1. Press the ONTROL + SHIFT + EJECT buttons in any order.
2. Ensure that they all are down by the end of the command and set them free from your fingers.
3. And you have your screen slept.
The first option I have provided CTRL+SHIFT+EJECT helps us take our system to Sleep mode. But to lock your screen in addition to switch-Off the monitor,
1. Press the COMMAND+OPTION+EJECT keys together and your done.
I thank my friend Girija for identifying this combination.