An display that you mount inside your house somewhere which wirelessly shows you how much electricity and/or gas you are using real-time.
Electric meters have the spinning disk with black mark, make an opto detector that reads it, then send out a radio pulse every time it goes by. The receiver picks up the pulse, and with the help of an MCU and LCD display calculates the power being used according to the simple power meter formula (wikipedia electrical meter) and shows you real time how much you are using. Connect it to your computer and plot the hour by hour trend! Updates every time the disk spinds around (about every 10s to 2mins depending on your power usage)
Gas meters have the same dials, but no spinning disk. use an optodetector to watch the half-foot dial which is the most sensitive, then do the same thing as above.
SOOOOO....how to send a radio pulse simply that can be received simply.....
Somebodys already done this huh...if so where is the info! Time to save money! Or race your neighbor and see if you can use more electricity than them! Make the street lights dim!