The JAVASCRIPT MESS project is a porting of the MESS emulator, a program that emulates hundreds of machine types, into the Javascript language. The MESS program can emulate (or begin to emulate) a majority of home computers, and continues to be improved frequently. By porting this program into the standardized and cross-platform Javascript language, it will be possible to turn computer history and experience into the same embeddable object as movies, documents, and audio.
We have a long way to go, but this open beta is now available