Inspire by: http://scratch.mit.edu/
Modk.it, semi-commercial, seems to be stalled: http://www.modkit.com/
Ardublock http://blog.ardublock.com
Scratch for Arduino http://s4a.cat/
Snap for Arduino ! http://s4a.cat/snap/
Minibloq http://blog.minibloq.org/
BlockyDuino (web based) https://github.com/gasolin/BlocklyDuino