In Australia, a woman was implanted with a real bionic eye, just like Steve Austin (Not Stone Cold #3:16).  It works by stimulating the retina, and that stimulation creates an image in the brain.  It has to be calibrated to make sure what the person is seeing is actually there.  This has several uses besides sight.  You could make just about anything appear I imagine.  Could you hack into the eye and make the person go on a simulated acid trip?

One funny note, and I am not making this up, the technology was tested on blind three mice first.  I don’t know how involved the farmer’s wife was in the overall process.