This is a vintage VFD tube clock that uses Ethernet for both power and data.
Monitor your water usage using a ThingySticks Water Monitor over your network with a WIZNet WIZ750SR.
Control RGB LED with a slider in simple mobile app. Uses a very, very simple message with TCP connection between Arduino and mobile app.
Monitor power supply and start emergency power generator in case of power failure.
How to make a simple remote display system with an OLED display and Arduino Ethernet. You can absolutely send your messages via mobile app.
I created a project for code development on the subject of vehicle tracking. It has a Linux computer and GSM board which includes GNSS/GPS.
Not much to it, really.