If you missed the post some days ago Tunaknobs is rotary controllers you can
attach directly on your device making you device one step closer to hardware.
It is hard to see how that would pan out,
but depending on what apps you are using and depending on your workflow it could be a good thing.
At the moment of this writing it has not gone live yet but I guess any hour now?
Go here to check it out:
There is also a radio interview that you can listen to from the other day
with Samuel Verburg of Tuna DJ Gear.
(They mention iPAD all the time but it is supposed to work the same for Android devices...)