Okay, this is pretty freakin' amazing; apparently, a number of the unique tiki mugs created by "Trader" Vic Bergeron, the restaurant chain's founder, were actually registered with the U.S. Patent Office. Here are a few of them:

Skull Mug
Sufferin' Bastard Decanter
Samoan Fog Cutter Mug
Cocktail Glass

You can dig through this directory listing for a few more non-Vic's mug designs.

Spotted in the Tiki Central Forums