apart from the ones already mentioned (rj-lib, automatonism, etc.), i think "orac" has not been mentioned yet. aimed mainly at the "organelle", but also kept very simple, like a kind of virtual pedal-board for pd-patches. https://github.com/TheTechnobear/Orac
and my own attempts in that direction: vvd at http://www.martin-brinkmann.de/pd-patches.html. no (apparent) userfriendly mixer though...
bis denn! martin