I blogged about my remote control related ideas a couple of years ago, but wanted to refine / extend that a bit.
The main idea is still the concept of being able to reward and punish her invisibly. This can be very handy in public places, where other forms of sexual stimulation or punishment are not possible. There are situations in play parties or in presence of kinky friends where that is possible, but let's say in an office setting, face-slapping definitely has the potential to upset a lot of other people, who won't understand.
One further idea is to use this remote control device for communication, at least uni-directional from master to slave (both in technical as well as bdsm context). The idea would be to use Morse code or a similar alphabet, delivered by very mild electro stimulation. The pulses in that case should be clearly noticeable, but not cause any pain.
So you'd have to teach your slave/sub/toy to read (feel) Morse code and interpret it. That's not too hard, and anyone is able to learn it with some practise. The text could be sent from a computer or (more likely) a smartphone, e.g. by means of an SMS based interface, or even a TCP/IP baaed protocol. The remote-controlled device could be connected via Bluetooth to the phone of the slave/sub.
As a result you have a way to give instruction to your willing sub, without having to speak them out. It's like having a secret language that nobody can understand, but even better in a sense that nobody is even aware of such communication going on. Just imagine a situation where you are in some kind of formal meeting, and you want to give your sub the instruction to open her legs slightly, for your or somebody elses benefit. You cannot really say it aloud, and even whispering it into her ear may be too conspicuous. So you can send that instruction via Morse code. If she doesn't comply, you can use the punishment mode and increase her motivation to follow your orders. If she complies, you could also reward her with some vibration.
I really like that idea of secretly and invisibly taking control of her, without having to speak up. I hope some of the readers equally enjoy this concept. I hope to turn it into reality with a willing submissive girl that wants to be remote controlled that way.