In reply to Captain Gear:
I'm not sure I would describe blender or the GIMP as simple and easy to use. Free, legal, powerful, versatile yes, but not easy to use. If you want to invest a bit of time and learn to use one, GIMP is great. Blender can do amazing things, but is IMO even harder to master.
If you want simple and easy, you probably want something tuned to what you want to do, without all the complex extras you don't need. So the question is what do you want it for? Photo editing? Realistic 3D rendering? Technical drawing? Making logos? There are a great number of free graphics programs about.
http://en.wikipedia.org/wiki/List_of_raster_graphics_editors#List
http://en.wikipedia.org/wiki/List_of_vector_graphics_editors#General_inform...