I did a little research to figure out what exactly has taken up residence on the porch ceiling, and think I have settled on them being paper wasps. The nest is about the size of my fist. The first thing that struck me about this is how delicate and perfectly round the nest is. The wasps chew up wood and spit it out, making a paper shell for their nest. Brilliant! How could this have occured by random, evolutionary chance? It looked like this little guy was working on buiding up the nest while I was snapping the photo. My fascination with them will end very quickly once they start chasing me around, so the bug moving company is coming to take them away today.
*Update* They took the nest and left a $75 invoice. I think that would make this my most expensive post so far.