Yes, yes, a thousand times yes. One thing that has worked really well is to take 3' x 2' whiteboard, rip off the frame and place it flat on your desk. It is fantastic for when you are talking to someone at your desk and quick diagram would help. At first people thought it was weird but people have gotten used to it and gets doodled on all the time.
Great idea! Behance also sells some whiteboard paint that you can use to turn most any surface into a whiteboard. Thinking of picking up a batch for my room.
It's also good for reminders and phone messages.