The MIDI Fighter is a MIDI controller made with classic arcade buttons instead of the usual silicon pads. Buttons are the same than the ones used by arcade games and old-school video game controllers: clicky, with 1mm of travel, bouncing back like a real drum, and built to endure massive abuse.
The downside is these buttons don't register velocity: they are either on, or off. But their tactility gives real physical feedback that other controllers lack, and the precision and reactivity of the instrument allow for high speed play and furiously satisfactory button mashing.
The current model is the MIDI Fighter 3D, which includes 4 banks buttons at the top, 6 more buttons on the sides for other uses, and a gyroscope, so the device can be tilted in any direction to trigger more effects. An editor allows to remap the banks and side buttons, and to define lights patterns and colors (because yes, this thing is quite the LED blinkfest.)
For people who need tons of buttons, the MIDI Fighter 64 offers a 8x8 grid.
I've been using a MIDI Fighter 3D daily for nearly two years, mainly to learn finger drumming with Melodics. I previously used a second-hand Akai MPD218, which I was happy with until I got fed up with its occasional unwanted note triggering.
I also like how compact the MIDI FIighter is in comparison. I don't have especially small hands, but the MPD218's large silicon pads feel less comfortable to me than the Fighter's tight arcade buttons.