Everyone is talking about Pokemon Go these days. We have already covered drones and other products you can pick up to help you find Pokemon like a pro. This guide from Adafruit shows you how to use a Raspberry Pi to build a Pokemon finder. The unit lets you know when you are close to catching a monster even when your phone is not accessible.
When a common Pokemon appears, the first LED on the Pokemon Finder turns on. The second LED lights up when you have a rare monster nearby. The third LED lets you know when legendary Pokemon are around. You are going to need a Raspberry Pi Zero, WiFi module, OTG adapter, and a few other parts to get started.