i think it would look really cool to suspend a "bridge" over the subs that holds the amps, but im assumming you probably dont have that much room between the hatch and the top of the sub box. still, that would be awesome... you could make the center section out of plexi to give a "floating" effect, and put some neon underneath to light up the subs. ahh!!! i have the craving to install somthing!!!! LOL
if you still have some space to the left and right of the subs, you mihgt be able to mount the amps vertically and parralel to the length of the car.
i always thought it would be cool to flush mount a pair of amps in the floor wells of the back seats. you would only need to take up about 4" of hieght on the floor, and you could fabricate a cover to put on when there are people riding in the backseat.
another idea: maybe you could mold the amps into the left and right panels in the backseat (and relocate the rear speakers if you have any).
BTW, i just started my install on the neon today, ive got some insane things im going to do, thats why im in such a creative mood, lol.