Etch VIN on Windows
Etching your VIN number on your car windows and windshield makes it difficult for a thief piece out your vehicle if it is stolen. The down side to putting your VIN on your window is that there have been reports of people being able to copy down a visible VIN number, going by the dealership, and getting a replacement key made. Proper ID and paperwork are required, but for some, knowing the right person is all you need. That is why some cover the plate in the window. I think it is a mixed opinion topic though as it still is a good idea.
A family member recently bought a 2013 Toyota Tacoma. Apparently, the dealership etches the VIN into every single window of every single vehicle as a theft deterrent. I did ask the dealership if they check the VIN of every single vehicle when it comes in for service to see if the car is stolen ... they told us 'No'.