A free app for Android, by Enrasoft.

Do you want to scare your family and friends? Camera Ghost Detector will help you do just that. With this app, you can use your smartphone’s camera to scan for ghosts and other paranormal creatures. If you see one, just move your phone slowly until the app detects it between the lines on the radar, and then you will see the ghost’s representation on your screen. Be careful, ghosts can be good but also evil, so if you see one, make sure you are not scared. You can play this game with friends and family and even scare them.