Slightly inspired by Max for Ableton live, I've added Pd for Radium
(Radium homepage: http://www.notam02.no/~kjetism/radium/)

Screenshot: http://folk.uio.no/ksvalast/radiumpd.png
Video: http://folk.uio.no/ksvalast/radium_pd.ogv

It's basically got the same features as Max for Ableton, but I haven't
implemented a modular note control system in Radium yet, so you can't,
for instance, make an arpeggiator in Pd that controls other instruments.
I will implement a modular note control system now though, because
of Pd.

But at least it's possible to use Pd to make sound effects and soft synths.

It's a bit rough yet, so I haven't released anything. You must build Radium
from source to get it, for now. It probably also only works on Linux.
I haven't tried  to compile on Windows or Osx yet.

To access pd, I have used libpd, but upgraded it to support several
instances, gui, and pd-extended:  https://github.com/kmatheussen/libpd