Pulsar timing arrays (PTAs) open a new band of the gravitational wave spectrum by building a galactic-scale GW detector. The strongest signal is expected to be the unresolvable background from supermassive black hole binaries (SMBBHs) at the centers of merged galaxies in the cosmological neighborhood. While SMBBHs are expected to be the strongest source of GWs, PTAs are sensitive to any GW signal in the nanohertz regime - I will highlight some of the potential members of this exotic menagerie. PTAs across the world have all seen the beginning hints of a signal from GWs, however we currently find no definitive evidence for the correlated pattern between pulsar datasets that is indicative of GWs. If we are seeing the first signs of the GW background, our models show that continued observations will lead to a detection with only a few more years of data. I will discuss detection methods for the various types of signals we expect to see, future prospects for multi-messenger astronomy of SMBBHs and how we might tune our galactic-scale detector towards the most interesting candidate sources.