Audacity (Audioeditor)
http://audacityteam.org/?lang=de

     
  HotPotatoes (Quiz-Generator)
 http://www.hotpotatoes.de 
     
  OpenOffice (Office-Suite)
 https://www.openoffice.org/de/ 
     
  Paint.NET (Grafikbearbeitung)
 http://www.getpaint.net