AFAIK, in Georgia, there is no law about the front of the car, but then we only have the rear plates normally. I see plenty of people running around with "unofficial" front plates of all sorts, and I honestly can't see how an airbrushed "Tweetybird" would be legal while a Euro-style plate wouldn't be...
I don't know if NJ has fronts, too, but that would obviously put a damper on Euro-style plates...
If you want to buy the plates, you can get them personalized from europlates.com or fancyplates.com, or a number of others (some of whom are probably sponsors - sorry). I ordered ours from fancyplates because they let me get away with an extra space so I could spell out "SGT PEPPER". It wouldn't be legal in the EU, but who cares
The other companies only let me have 9 characters including the space, and leaving out a letter looked funny. They also have tons of custom options for logos, etc. The downside is that they're in Northern Ireland, so be prepared to wait a few weeks. But shipping is pretty reasonable (I paid $34 all up including shipping).
Right now I'm waiting for a frame from europlates, since I didn't order one to begin with, and I think they look better in the frame than not. A friend from England says nobody there uses frames (there may be some differing opinions here), but I like them, so there's another $17.50 (incl. shipping). Oh, well...
Enjoy!
-Eric