Here is a quick mockup for a "walk-trough" music sequencer
i.eho.st/pjs9f88p.jpg
The idea is to have an option to set a particular note to an object, then drop several of them as a melody on the ground. Fellow glitches would then hear the song as they pass by.
Here I chose some small shiny objects, because they don't have any use atm. They could be turned into a "music rock" with a tinker tool for example.
Each note is activated when the object highlights, so it all depends how fast or where you walk.
Actually, everything that passes by could activate the notes, so it would work with cubimals as well.
A more complex approach would then be to use those cubimals (instead of childish races) to play more interesting pieces of music. You would be able to set a program, a bit like for garden gnomes, and assign it to the toy, depending of it's features (a piggy may only go straight, but flying cubimals could jump back to the start and do loops). For example, you would tell you pig cubimal to go back and forth five planks to play a beat, while your butterly cubimal would fly ten planks left to right in a loop to play the melody.
I've seen amazing music interfaces in other games, so I hope we can have this kind of stuff in Glitch as well. That concept doesn't seem too hard to implement as most of the mechanics are already in-game, and I know that Stoot is very interested in collaborative step-sequencers.