Lucas Meadows stashed this in HTML5
There's a small amount of Visual Basic and a single .swf file in the JSNES github, but those seem to be for handling browser edge cases.
He doesn't have that many ROMs yet, but hopefully the collection will grow!
What's really interesting is that, down the road, we might see some WebGL-based emulators of 5th generation consoles (32-bit platforms like N64).
I know of no decent emulators for 5th gen or later, but I'm hopeful that in the next few years someone like Firshman will make it happen.
So when can we start playing these in a browser, please?
More importantly, when can we start playing them in a MOBILE browser?