USB On-the-go MIDI Keyboard with Nexus 7 Has anyone successfully used a MIDI Keyboard (through USB OTG, specifically) with a Nexus 7? (I am not looking for commentary on the particular keyboard, but please state which you have used.)
You can use any standard Midi keyboard with your device. (src) 

There are several keyboards with Korg and Roland. Choice of the device is all yours. But unfortunately there are reports that your nanopad is not working with this as you asked in your original question. (src)

You may want to verify that with the manufacturer first, before you go for a new one. Once you have a standard Midi device (which does not require driver installations), you can use apps like USB MIDI Monitor or Grand Piano



Note: You can try eBay for good solutions. Visit a local music store and check compatibility before you buy as Izzy suggested