Scan and draw ruff sketch of distances ahead just like RADAR using UltraSonic Distance Sensor.

GeekTurnik is the first WiFi-connected pull-up bar.

Modify RC boat and maneuver using Windows Phone or Window Laptop.

I built myself a voice controlled home theatre, with background light, screen and projector control. With an ESP8266 and an Arduino Nano.

Small temperature/humidity/atmospheric pressure monitor using Sigfox to transfer the data. Powered by solar energy to monitor beehives.

Building a customized bluetooth controller using Arduino.

You can sniff an KNX RF network by an CC1101 radio transceiver. I sniffed my Siemens Synco Living Home automation system