For printing code, obviously. Personally, I do that when doing big refactors on some module I didn't write (or wrote it so long ago I don't remember much), or basically when I can't focus. I actually learned that from 'edw519, who summed up my worries about paper use with "Paper is cheap. Focus is golden.".
I recently used enscript [1] to create pdf's from code, can recommend.
Also, why do you want that feature?