This is a great idea to improve the appearance (and usability) of stacks in Leopard.
Stacks is pretty much Leopard’s only non-eyecandy change to the dock, and it had the potential to be pretty handy, but the fact that the icon representing the stack is whatever the top file in the folder happens to be really ruins it (for me at least). However, if you haven’t yet given up on stacks and thrown them off your dock, there is a solution: overlaying stacks icons.
In essence, these are just small-ish semi-transparent icons that are permanently our top icon. This picture explain it best (before & after):