- Neighborhood watch would be helpful - why is this car creeping around the area?
- With enough coverage could weed out thieves / crimes
- Find your elected official and see if they hang around strip clubs
- Find where the kid dating your daughter is hanging out
- Employee said they were home sick? Find his plate and see if it isn't out driving around
- Auto tag police plates and have real time police locations. Like those spot a cop apps to help avoid tickets
- Road rage allows for revenge. Get cut off? Find where the car is parked and put bird seed all over the car, etc
The sky is the limit on what would be created with an open source backend DB. I'd put a cam in the yard and in my car. Sounds amusing.