Here we're experimenting with a fretboard for instruments like guitar. The opaque discs represent the tonal center (root note) of the key. The next brightest are notes of the pentatonic scale (in the same key). The dimmest are the rest of the notes in the diatonic scale.
Erik van der Neut has another take on this. It's interesting and has some nice features that mine doesn't. It also has more scales.
The circle of fifths on the right highlights the chords that, along with the scale, fit in with a particular key. Note that this is designed for the twelve major and twelve minor keys. I'm kind of winging it for the other modes and scales.
Note that this just for switching between major and minor keys to highlight the idea that the notes stay the same and only the center changes. This button might do wierd things with other modes.