hey, stacks are really quite interesting.
i've made a stack myself, all the cymbals on it are totally busted stuff mind u
i've got a pair of zildjian 14" hats and 12" hats on the stack, and they make an awsome sound effect.
To make the stack sound awsome, invert all the cymbals u put on there (turn them bottom side up) and then, play it like u would a china cymbal really. hard to explain, but check out Jon Theodore's stock on the right side of his kit to see what i mean, he has an awsome sound from his stack.
P.S. put the bigger cymbals on the out side of the stack (the top and the bottom of the stack) and put the smaller ones in the middle, this gives the cymbals room to move, so it gives them a more trashy sound when hit, instead of a crappy chick/clicking sound.
I've been playing around with this idea. I put my 18" Wuhan China on top of my old B8 ride. Pretty interesting......but I don't know if I'm sold on that combo. It will take some experimenting to find the ideal effect.