Adafruit’s NeoTrellis has a nifty microcontroller at its heart, but you’re going to get one because of what it’s powering: A reprogrammable light-up keypad. Running through Adafruit’s always-excellent tutorials will get you to load up a drum machine, or put sound effects at your fingertips, one per button.
The NeoTrellis has a headset jack, microphone input included. Aside from that, connecting external devices isn’t really what this controller is about: There’s just a couple pins accessible to the outside world. If you want to attach a load of sensors and actuators, Adafruit has no shortage of other boards better suited to the task.
This one is a pre-built IO & Audio device that lets you use those microcontroller smarts to take over how it performs. You have a field of 24 glowing buttons to work with. Each button can change color as you see fit. Outputting sound in response to button presses is the obvious use.
I hope we’ll see more devices like the NeoTrellis kit: Ones that give the user a head start on the hardware side of their creation.