So you would like to control your LEGO trains and other Technic models with your smartphone? The BuWizz 2.0 Ludicrous has you covered. It combines with your iOS and Android devices to give you 100ft remote control capability via Bluetooth. BuWizz has 4 ports for motors and lights.
BuWizzhas 4 speed modes (slow, normal, fast, and ludicrous mode with 3x power). It weighs under 50 grams. The below video shows what you can do with it:
You can find out more about it here.