Websites
Swami-
Soundfont editor - http://www.swamiproject.org
Musescore-
Sheet music - http://musescore.org
Calf Studio Gear-
LV2 plugins - http://calf-studio-gear.org/
Linux Studio Plugins-
LV2 plugins - http://lsp-plug.in/
Analog Modelling Synthesizer-
LV2 plugins - http://amsynth.github.io/
XSynth DSSI-
DSSI plugins - http://smbolton.com/xsynth-dssi.html
Computer Music Toolkit-
LADSPA plugins - http://www.ladspa.org/cmt/overview.html