Ditto. I doubt it's a SCSI port or anything of the like, given that it's composed entirely of little 14/16 pin chips. A high-res picture of them (or list of part numbers) could clarify if they're memory chips or just a big pile of TTL goo. What's most interesting is the fact that the PCB is missing the Nubus transceiver chips and there's no wiring running to the bus connector. The possibility exists that whatever circuit is implemented on that board hasn't anything to do with a NeXT workstation and someone was just using the card as a piece of perfboard to prototype something unrelated.Some more hi-res pictures of the chips might give us a better idea of what is does (or should I say did).
(Or, the in-between possibility, whatever's on there is designed to modify the output of one of a NeXT's standard ports and connects to them via external jumpers, only using the card cage connector to provide power for the circuit.)