Another of my thift store finds (and likely the oddest) is an iRobot Roomba 530 for $60, along with its dock, power cord, and two virtual walls. I plugged the charger into the base, sat the Roomba on it, and it started its “deep charge” cycle.
After charging it for 24 hours, I started it up. It backs up, turns, and backs up again, continuing in this pattern for a few rotations before stopping with an Error 9, which the User Manual states is a dirty front bumper.
TODO: Gut an old mouse or other device for its mouse-wheel IR sensor to replace the broken one.