You could design a single board computer on a Zorro card (it was done with bridge boards, after all) running an embedded operating system and a custom software interface that autoconf'd to provide bsdsocket.library, a raw SANA-II device, a P96 chip/card library, an AHI device, etc. Ambitious and expensive, but cool.
Another cool option (for people with PCI busboards) would be software support for a Killer NIC, which is basically a PCI-based SBC. Depending on the bus speed, you could host some features (display, audio, etc.) over IP and make the translation transparent on the Amiga side. At the very least, it would make a nice, fast IP stack for anyone willing to write a bsdsocket.library-compatible interface to it.
EDIT: Much of this was attempted by the Siamese system.
