Umm there's some stuff there I wouldn't mind myself!
The thought about putting the fan at the top (at the back I assume)is, sort of, good as far as I can see. But, where is your power supply? This will generate heat so I would have thought this should go at the top (with its fan at the top with it, obviously), and then your other fan just beneath it.
Or do you mean on the top surface? Never seen this before (but that doesn't count for much!), but if so, if your computer is anything like mine, this surface will be covered in all sorts of rubbish within minutes!
Don't forget, if you want more cooling you could always add a fan at the bottom front blowing IN.