Adam and Kumpf from Labs teague have put themselves in challenge to construct a water meter to keep track of water usage from tap. Instead of using standard water meter they decided to use a cheap water meter that are used in PC cooling system. They are easy to interface with microcontroller. Additionally they put a thermistor to read water temperature.
They used a YellowJacket Arduino board with WiFi connectivity. With this they pushed sensor data to web so it could be seen from anywhere with internet access.