Re: Crib in the bathtub?
Re: the closet, you could put a crib or PnP in a closet if you took the doors off. Then it's just a funny leftover piece of the room. Maybe with a three-panel screen (you know, the decorative kind) in front?
Granted, it might not fit anything BUT the closet, but it COULD work (and be reasonably legal).
Check out apartmenttherapy.com - I'm pretty sure they've run pieces on small-space cribs and such.