[InnocentB]

I think the first place I saw this technique used was in EmuDX, which had swapped-out graphics for Pac-Man, Ms. Pac Man, Galaxian, Frogger, and Donkey Kong. This was around 1999 or 2000. Its site no longer exists, but here's a mirror: http://www.arcadeathome.com/emudx.phtml.

I was always sad it never really caught on, I think it's a great way to revitalize old games while preserving gameplay.