Calligram
Definition: A word, phrase or poem in which the handwriting or font used form part of the focus.
Thanks to Chris from Paris for using this word in an e-mail to me, in the context that Google is a calligram of an Owl - the double 'o' forming the eyes of an Owl.
The creation of the term is attributed to Guillaume Apollinaire (August 26, 1880 - November 9, 1918), a poet, writer, and art critic. Shortly after his death, Calligrammes was published - a collection of his poetry in which typography and layout adds to the overall effect. He is also famous for coining the word "surrealism" somewhere around 1916.
Another term, Concrete Poetry, was coined in the 1950s to mean the same sort of thing, althought I think the term is limited to just poetry.
Frontispiece
Definition: a decorative or informative illustration facing a book's title page.
I'd never head of this word until one of my photos was used for the frontispiece of a book called 'Dragonfly' by David Chandler.
Vermiculation
Definition: a surface pattern of dense but irregular lines.
The word comes from the Latin vermiculus meaning "little worm", because the shapes resemble worms, worm-casts or worm tracks in mud or wet sand. The word may be used in a number of contexts, for patterns that have little in common. The adjective vermiculated is more often used than the noun. I've never seen this word used so many times as in owl species descriptions.
Guttation
Definition: the exudation of drops of xylem sap on the tips or edges of leaves of some vascular plants, such as grasses, and a number of fungi.