Here's a thought:
a 3D accelerator-graphics card with hardware MPEG1+2 decoder that allows AGA graphics overlay (with outline capability) for both ZorroIII Amigas and a 1200 version. Perfect suggestion for arcade games! Its own firmware should be allowed to upgrade to handle more complex 3D graphics. 256MB max RAM DIMM socket(s).
Everything else I would probably see on a mediator like 100Mb ethernet card, 16bit sound card and more.
:-)
