pd is a graphical multimedia programming environment availible for all major platforms.
→ pd-zmq external providing zeroMQ bindings for pd
This patch here makes some --aehm-- glibbery noise, but visualises quite beautiful patterns out of it. if you don't mind the overcomplicated insides of [blipper], it's very simple and only requires GEM to run.
→ simple sequencer
This is simple 4 track/16-step sequencer, developed as working material for a beginner workshop.
It is almost written (or drawn?) in vanilla-pd, were it not for the pattern-saving using footils/sssad.