Audacity (Audio editor, Open source)
GIMP (Graphic editor, Open source)
Inkscape (Vector graphic editor, Open source)
Blender (3D RAD, Open source)
Debut Video Capture (Paid) Screen video capture
There's just not one list, nevertheless open source softwares can help reduce the price of your toolbox with more than decent alternatives to otherwise overly complicated softwares.
Also you can download and use those without being a pirate.