One example is hooking up any alternate instrument with midi to interesting tools like Rock Band 3, which has a "Pro" i.e. real music mode. In the case shown above, a jammer has been hooked up to an Xbox running Rock Band 3 Pro via a couple of midi connectors. 

 It has just recently become possible to hook up midi instruments to a high-quality, training video game like this.  The ingredients (beside the game console itself) are:

1. A decent game: said game is Rock Band 3, and it has a “PRO” instruments option; the option to select having a real instrument (midi) hooked up to it
2. A Gaming console (Xbox/Playstation/Wii) to Midi input interface:  Rock Band 3 midi PRO-Adapter. One plugs a standard Midi cable (non-USB) into it.
3. An instrument with standard midi-out, of course.

1. A decent alternate keyboard or other instrument:  even a PC keyboard will do, although it has definite limitations.  The raw, unmodified Axis-49 will work, but the signal has to go through a computer.
2. Midi-routing software to convert the instrument’s production (which comes in on the “Midi-In” logical buss) to a signal on the “Midi-Out” buss.
The new Midi Integrator does this well and there are doubtless others. Midi Integrator is free, works on Win/Mac machines, works as soon as installed and is easily configured.

Here are the connectors used in the example shown.