Here is a very handy tool that every agent needs. Rather than using a tape measure to get the room dimensions, use a laser measurer to get accurate measurements in a fraction of the time. I use the Bosch GLR225, which is accurate to 225'. Bosch also makes one for distances up to 130' (DLR130) for less than $100 (perfect for residential properties). Since I create as-built drawings for commercial buildings, I need the extra distance. It is very easy to use and works great, I highly recommend it.
When showing homes, it could be very handy when a buyer wonders how big a room is.