"Twenty Things to Do with a Computer" Revisited

I'd add to your list

  • Making animations with interactive parameters.

(That's my favorite)

One can interactively animate a fractal tree or plots/diagrams (math); it can be a virus spread (biology); it can be gravitation and/or magnetism acting on a chain of linked elements (physics); it can be text editing in text editor (office tool); it can be Benham disc; it can be various size/shape 'pointilism' (art); etc etc etc