You can enter the realm of contact printing with 4x5, opening the doors to platinum printing, etc. You could do it with MF, but it might not be so appealing.

Of course, that's a slippery slope, as Bob suggests. You start contacting 4x5, you'll really want to contact print an 8x10, no, 11x14! (Best I can do at talking you out of it...)

-chuck