Andrian have developed an AVR based thermometer that can be mounted on a wall. He designed a PCB with two holes. Ok this is convenient, but lets look whats inside this neat thermometer. It is based on Atmega8 microcontroller that reads temperature from DHT-11 sensor. This one is used to measure outside temperature and humidity. For inside measurements there is a LM35 sensor used.
Thermometer is capable of displaying temperature in Celsius and Fahrenheit. Additionally it sends temperature values over USART. So Andrian managed to plug an USART to Bluetooth module so he could monitor temperature remotely with PC or mobile phone.