Question about putting a Macbook Pros display to sleep

Is there a simple way (i.e. a button/key) to put only the display of a macbook pro to sleep with the lid open so the computer can still run processes and programs for extended periods while I am away or must one simply wait whatever time they allotted the monitor under the system preferences?

Click on the Apple in the top left. Then go to System Preferences>Expose & Spaces. Make sure you are on the Expose tab. Select one of the Active Corners to Sleep Display. Close it and you are done, just move the mouse pointer to that corner and the display will turn off.