This is a WiFi doorbell notifier. It uses the ESP8266 powered by the doorbell transformer, along with an OLED and PIR sensor. The OLED displays a flashing bell icon and shows count and time of rings. The web page also displays a list of rings and has controls for pushbullet and display features, plus real-time event streaming. I use the PIR to turn the display on since it can’t reach a good outside location. It also gets weather conditions and alerts. Very few components so it’s fairly cheap.
Here’s the project: https://github.com/CuriousTech/WiFi_Doorbell