We had a group of people at the Heard Museum for Sketchcrawl #28 today.  If you need ideas for creatures or monsters, the museum's Indian art gallery is definitely the place to go.  They had so many cool katsinas and masks, I hardly knew where to start.

Mask of Torim (Tampaleo the Rat Flute)

Navajo Mudhead Katsina with Drum

Mohave Animal Figure with Dress and Beads