I did what you are asking earlier this summer. CruiserCustomizing.com has a lot of options in the small and large size.
Maryland also has the giganto bike plates. I scanned my plate, shrunk it to the smaller 4"x7" size than laminated it. I think it looks much better in the smaller size.
Here's a thread with the info/pix.
http://www.bonnevilleamerica.com/forums/...;page=&vc=1
