Okay, so if you needed any confirmation, I am now officially an idiot. I didn't realize what the orphaned lspdev package was doing until after I tried to manually delete many of the files removing it left behind. Only to realize that I had actually removed pretty much all of /usr. Fortunately /home was a different partition, and dpkg --get-selections > file let me record every installed package in a way that let me quickly and easily reinstall my system (quickly because I have a mirror of debian here on the network ;-).
