Prototype Z-Corp style powder printer by SandBox. Inkjet wetting of plaster to make parts.
I think this approach will really take off when Memjet nozzles (video below - warning, turn your volume down) becomes readily available and repurposed for 3D printing..
In theory, it should be possible to print ~0.1mm resolution at 0.1mm layer height, 12 layers a minute - or roughly 60 mm/hour for a bed full of parts. (My assumption: 3 seconds to lay down a fresh layer and wet it, 2 seconds to dry. Repeat.)