Paul wanted to know time spent on shower each day so he built Arduino based shower time analyzer. It simply checks times when someones enters and leaves shower with RFID reader. Time is counted with precise RTC clock.
It wouldn’t be fun if this wouldn’t be connected to internet. So Arduino is also featured with Ethernet shield. With thingspeak API it was really easy to publish data on internet. Now watching charts you can decide weather you are wasting water or not.