NESbox
Emulator of NES, SNES, Sega Mega Drive, GameBoy video consoles
...It’s written in ActionScript/Flash, and the project includes SWF binaries so you can embed the emulator into web pages. The emulator allows users to load ROMs and play them in their browsers via the Flash plugin. It’s licensed under the MIT license, meaning it’s quite permissive in terms of reuse. While Flash is an aging technology, the project remains a practical way to access old console gaming via browser, as long as Flash is supported or available.