I have only run across four official name tags in my search through the old Velvet Pawz and Nightshade Petz websites. Other colors and styles will be released by Acid Trip periodically, so keep an eye out.

Official text from the Velvet Pawz Website:

Name Tagz

You can have a name tag for your Petzies if you like. The small ones are ideal, but if your Petzies has a long name, you may prefer the bigger ones!

Velvet Pawz Official Name Tagz:

Acid Trip Name Tagz: