Video A Versatile and Rugged MIDI Mini-Keyboard (Video) 56
The K-Board won a "Best in Show" award at CES 2015. Plus, as Timothy said, "I always like pour and stomp demos." And it's totally cross-platform. If your computer, tablet or smartphone has a USB port and (almost) any kind of music software, it works. In theory, you could hook a K-Board to your Android or iOS device and use it to accompany yourself while you sing for spare change on a downtown corner. Or noodle around to get a handle on a theme you'll use in your next major symphony. Or...?