Searching for "SCNB-1.0" actually turned up some results -- apparently it's a Photoshop accelerator card (hence the DSP chips). Supermac also slapped their logo on this card and sold it for a while. 

It probably won't work with OS 7.6 or later, so I'll have to reserve it for one of my older machines running 7.1 or 7.5.5...