This is a good idea - i'd find it immensely more useful having links to the actual source, though. I don't have time atm to go through the list and add links to source. khteditor appears to be a port of pygtkedtor to Qt (I haven't actually tried it), but the source has some good things in it. maesynth has a cool method of using images to draw the keys on the keyboard and using them to play sounds instead of normal Qt Widgets.