In the tradition of hyrdofluorochloroethylbromobenzylnitrate, I suggest we do something with the IUPAC name for titin.
It's ~190,000 characters long.

I will be nice and not paste it, you can find it here: http://othyr.com/titin.html
(I would recommend verifying that against a few other places, as if I'd hosted it, I'd probably insert some random phrase in the middle)

At the very least it could be set to word wrap and form a background for the program. I suppose we could do the same thing with pi, or e...