Emulation und Decompilation of the Arcade Hit "OutRun" (reassembler.blogspot.de)

Best thing about Outrun? The music.

This is not "emulation", he's re-writing the engine in C++ using the original ROMs' data as input. Of course, by reverse-engineering the machine code to the required level of detail, plenty of bugs in the original game are found. Very impressive.

Rewriting games and applications based on a disassembly is an impressive feat, considering the amount of hacks which end up in production code.

Similar projects i can think of off the top of my head:

OpenDune, OpenTTD, ScummVM, OpenTyrian