The exponential growth of technology
I liked The Singularity is Near by Ray Kurzweil. (He invented the first decent digital piano and the first decent voice recognition software.) But the best part of the book by far was the graphs. I just found that they are all online, so I thought I would share them with you.
The first few are gimmicky and not much use, but the others are practical. For example, I want to pay one cent per gigabyte of hard disk space. How long do I need to wait? (Answer: five years.) Or, I want a computer that can accurately simulate every neuron in the human brain on my desktop. How long do I have to wait? (Answer: about 20 years.)
Also interesting is the drop in U.S. war deaths, and the increase in resolution of non-invasive brain imaging.
Be sure to keep in mind that these are log plots, so a straight line is really an exponential curve.