Has anyone made one? I am wondering mainly because it seems like a smart villain ruling a dungeon or other complex would put creatures that can see invis at every entrance and other checkpoints.
Not as such, but scent or blindsense will be the most common invisible creature detectors and searching for one of those will get you a lot of options. There are counters to those counters too of course, scent especially.
There are many ways to ward an area against invisible intruders. The Invisibility Alarm spell can be made permanent, pressure-plates can connect to a silent alarm, Magic Altars can grant worshippers True Seeing, (Un)Hallow can integrate Invisibility Purge or Dispel Magic, ... or simply, a closed door. :)