Thermistors are variable resistors that change their resistance with temperature. So I used a thermistor and 8 LEDs to create a LOVE machine. The user can put his hand on the thermistor to test the temperature and the heat of his love, as a result, the LEDs might light up (starting from the upper left one, each LED lights up counter-clockwise) depending on the heat.
The program also shows the temperature of the thermistor with signal monitor, which shows like this:
The schematic circuit: