I have a function of three variables and am interested in plotting the zero level surface:

f(x,y,z) = 0

Is there a simple way to plot this level surface in 3-D without having to resort to meshing up x and y, and solving for the z that satisfies the equation?  I can do this, but it gets messy because there are anywhere from 0 to 2 solutions to the equation for each point in the x-y plane.

The mplot3d examples all seem to calculate the z-data simply from simple functions of x and y.