The same way we support Frei0r, we should be supporting LADSPA for audio. It's the same idea of a simple audio library and it contains many plugins.
http://www.ladspa.org
Among other things, LADSPA supports "hints" like Drone does (eg. min/max values of a port).
http://www.ladspa.org/ladspa_sdk/
http://www.ladspa.org/ladspa_sdk/ladspa.h.txt