Madscifi and Johnrpm of the RepRap Forums are showing some excellent results from their DIY inkjet print head. Constructed using a piezo buzzer as a control valve, it can be used to drop small beads of water onto a bed of sugar, building up a crystal object layer by sweet layer. John designed the printhead, and madscifi has been refining the nozzle for more reliable delivery. The project is still very much a work in progress, and if you want to get involved, check out the discussion over in the forums.
Printing in sugar with a DIY inkjet print head