a) A mishmash of files that clutter your desktop or file folders after you've downloaded all the fonts you can think of.
b) A work of art or writing that places most of its creative value in the use of many different font faces.
a) "Dude, I've got to reorganize these folders. It's just one big fontage in here."
b) "I suck at graphics, so I just made a big fontage for the t-shirt design contest."