So glad someone posted this. Basically everything Bret Victor does is gold. His website [1] has a bunch of great things he's written/done; two of my favorites are The Ladder of Abstraction [2] and Learnable Programming [3].

[1] http://worrydream.com/

[2] http://worrydream.com/#!2/LadderOfAbstraction

[3] http://worrydream.com/#!/LearnableProgramming

Came here for this. My favorite talk of all time. Easily had the most impact on my career.