Baby monitors have gone from your average audio device to the overly complex it seems. Now we have video and night-vision cameras and this latest version which has a motion sensor pad to detect all movement or lack thereof.
The pad does have one very major perk, it could detect early warning signs of issues related to Sudden Infant Death Syndrome. Which would put many parent's minds at ease, since that is a scary thing.
The device tracks movements through the pad and provides audio and visual information that the parents can carry on them while trying to clean up really quickly as the baby sleeps. Although I think a beep going off every time they moved would drive me nuts after a while. The monitor is being sold for right around $80.