Bleep Bloop Blertz

Bleep Bloop Blertz: Music Macro Language is a tiny programming language for making music. If you want to work with it yourself you can start with the guide, or skip ahead to some results with handy in-browser editors. Besides being supported by many BASIC implementations and having a compiler for more than ten consoles, it can be used by composer characters in the Mabinogi MMO, which has produced a number of blogs dedicated to producing MML tracks for use in the game.

As a bonus, Autotracker is a Python script that automatically spits tracker files with full songs. See also bytebeat (previously).