Take a picture of the license plate with your camera phone and send it to the “your lights are on” website.
The web service OCRs the license place (should be easy, right?) and one-way hashes it. Look up in the database and send a SMS/mail message/automated phone call to the owner.
You would have to register your license plate numbers and preferred method of contact.
Then, when I see your lights on somewhere, I have a way of notifying you. Of course many new cars have auto-light-shutoff features, this maybe is not so interesting. Maybe instead of “your lights are on” it could be “Hey, you’re parked in my spot!” or maybe “Hey, I’m towing your car”. Register your address and I can send you messages like ‘your sprinkler system is broken and flooding your yard’ or something.
The idea is to decouple having to know who owns or operates a thing with sending it a message, while also anonymizing the sender.
I have wanted something like this too, but you are missing my reasons. The reasons I have thought of, are:
* “Your tail lights are burned out”
* “You left you gas door open”
Things like that. Some people go months w/o knowing their lights are out..