Hmmm, weird, I was just thinking of this yesterday... Actually I was wondering if there was a way to "activate" the PC slots without a bridgeboard but, the more I thought about it, the more I realized it wouldn't be real useful without a CPU. Anyways, the reason I was thinking the same thing is that I have an old 16bit (complete and like new) MPEG decompression board that would be cool to utilize. Minimum requirements are fairly modest; 386/win3.1/2MB/DOS5 etc. It came with all the software to playback VCD's @ 24bit/MPEG-1 video and MPEG-1&2 audio using a simple passthru cable. I'm building up my A2000 to be a King Kong multimedia machine w/toaster functionality (WIP). Anyone brought up adapting a Pi to ZII/III? Good post ElPolloDiabl!
Over at Atari-Forum.com a user Jookie has built a device (Cosmos Ex) that interfaces a Raspberry Pi with the ST. The Pi acts as a HDD interface, network interface and FDD emulator. It will decompress ZIP images etc for you to.
Now.. an Amiga version of this could be an interesting idea...