Audio Detection

From making a thread in the wrong section and getting some feedback. I was wondering how many people have used or been successfully in using either of the two audio detection circuits or think would work best with arduino.

http://www.sparkfun.com/commerce/product_info.php?products_id=8669 http://www.robotshop.ca/inex-sound-detector.html

Not used any but ether of them look like they would be well suited.