Data from pulsar timing arrays (PTAs) — a collection of rapidly rotating neutron stars in our galaxy — have recently provided us with a new way to measure gravitational waves. It is generally thought that the gravitational waves measured using PTAs come from supermassive black holes orbiting each other in the centers of galaxies, however they may have even more exotic origins. I will describe what it takes to construct a PTA and how the data we collect gives us insights into some of the most extreme objects in the universe.