Update: I removed the copyrighted image of CatDog on February 24, 2009.
Our new metadata mascot at work is the cartoon, CatDog. We were writing some XQuery with practice strings: "cat", "dog", and "catdog".
My colleague pointed out that the cartoon is a metaphor for metadata: Cat is traditional AACR2/MARC cataloging: cautious, territorial, and finicky. Dog is non-MARC metadata: fearless foregoing into unknown territories, snooping around, trying new things...
So, now we have an image now that expresses our hybrid, mixed-up world of cataloging and metadata in the 21st century!