One interesting side story and addition to the Atari vs. Nintendo battles - Tetris. Atari had licensed the game for arcades, while Nintendo licensed it for consoles. Considering the NES the same thing, Atari made a version of the game for the NES under the Tengen brand. Nintendo, on the other hand, made their own version of the game for the NES. A legal battle ensued, with Atari losing in the end, and Tengen's Tetris was pulled from store shelves.
The sad thing? The Tengen version of the game was a far better port than the Nintendo-created version.