BTW, I just used a TQFP form factor of an Atmel chip so I could get it and the rest of the circuitry inside the outlet, but one could also use an arduino, https://www.adafruit.com/search?q=arduino
or one of the other boards they sell here and then feed it into the outlet to the OLED or just a display like they sell here, "http://www.adafruit.com/search?q=oled
" mounted somewhere.
If you're new here, be sure to check out all the new things that they add all the time and the online videos they do weekly.
Good luck, and have fun!