I have used newspapers for awhile outside the cage.  It seemed easier
than having litter spilled everywhere, and has better traction for one
of my ferrets whose feet slip in litter.
 
I just started using those "puppy pads" since I figured they're more
absorbent.  They are more absorbant and also hold in the odor.  They
have a plastic lining so no more leaking through to the floor.  Only
downside is they are of course more expensive than using newspaper.
 
Risa
[Posted in FML issue 4822]