The other day I was talking to a person how sometimes I have a lot of downtime due to the nature of the work and that is why I am always prepared to do something so that I am not wasting time. For example, those times are a great opportunity to say update yourself if you are a casual investor or if you run even a simple business like say selling stuff online.
That reminded me of a news clip I saw way back where there were high school students that actually ran businesses online on the side while attending school. During breaks they would literally whip out their cell phones and start to contact customers. A more common theme was students jumping onto a laptop during lunch breaks to keep track of a web based business.
Just goes to show that if you really want to you can maximize your day with side businesses to help you generate more income.