Addon developer suicidalkatt has created a theme for TidyPlates that mirrors Blizzard's own April Fools creation, the Equipment Potency EquivalencE Number addon. You can pick it up here at WoWInterface. The addon requires Gearscore to run, as it uses the player's value from Gearscore to scale your bar. Just make sure to select the EPEEN theme on TidyPlates after you download and install the theme.
stolenlegacy over at WowAce has also begun work on his very own E.P.E.E.N. meter. The addon is in its very early stages of inception, but I can't imagine it will be anything less than amazing.
Personally, I am very excited. My number will most likely be gigantic (and not compensating for anything, whatsoever). With a true E.P.E.E.N. system in place, maybe we can finally kill GearScore once and for all. Rather than be judged by a number cobbled together from disparate item values, we can be judged by the size of a bar cobbled together from disparate item values.
All kidding aside, I am happy that World of Warcraft's user interface allows for fun stuff like this to become realized and that Blizzard has a good sense of humor when it comes to the addons the community could potentially come up with. While we're on the subject of bringing April Fools jokes to life, can we get another petition going for two-headed ogres?