Plot function on a sphere

Hey guys, I was wondering if anybody knew how to plot a function, say x^2+y^2, on a sphere, where there would be a uniform sphere except at one specified area there would be this function [either denting into the sphere or morphing the sphere so that it is sticking out a bit].

Thanks in advance.

[Ryan]

is this what you are looking for? http://math.boisestate.edu/~wright/montestigliano/PlottingOnTheSphere.pdf