elliptical machine and sneakers

Anybody have thoughts on a good pair of sneakers to pick up for use on
elliptical machines.  I had my trusty old pair of sneakers for about 4
years, and they have suddenly fallen apart, so I need to get a new
pair.  My workout habbits have changed somewhat, and they weren't that
great anyway, so it's probably a good thing.

I've been doing a lot of cardio on the elliptical machine lately, and
really prefer it to other machines.  I generally do 45-60 minutes 3-4
days a week.  The only problem I have is that because the pressure on
the ball of the foot is constant, they tend to hurt or feel numb after
a while.  Not horrible, but if I could eliminate that, it would be
good.  Also, since the impact is much less than running or even
walking, is there a type of shoe that would be more comfortable?