Having trouble learning the violin? Finges not moving as they should? All thumbs? Just be patient. In the future there will exist devices that take control of your limbs and use electricity to make them move on their own.
One such device, unabashedly called PossessedHand, already exists and does exactly that by way of subtle electrical pulses sent into the wearer's wrist and fingers.
[T]he PossessedHand as it's called can be strapped to the wrist like a blood pressure cuff and fine tuned to the individual wearing it. The PossessedHand sends small doses of electricity to the muscles in the forearm that control movement, and can be "taught" to send preprogrammed signals that replicate the movements of normal wrist and finger movements, such as plucking the strings of a musical instrument.
Though the signals sent are too weak to actually cause string plucking, they are apparently strong enough to cause the user to understand which finger is supposed to be moved, thus, the device might be construed to be more of a learning device than an actual guitar accessory.
Beyond that, the mind races. Having trouble signing to a deaf companion? Strap on PossessedHand and boot up a sign language program. Even if you have no idea how to speak sign language, the software will subtly mold your hands into the correct shape. You aren't really "learning" the language, as the brain plays a passive role in the process, but it'd still be an effective communication tool. [Rekimoto Lab via PhysOrg]