OpenEmu is about to change the world of video game emulation. One console at a time...
iOS & tvOS multi-emulator frontend, supporting various Atari, Bandai, NEC, Nintendo, Sega, SNK and Sony console systems.
A crossplatform application API, powering the crossplatform gaming platform RetroArch
Libretro is a simple but powerful development interface that allows for the easy creation of emulators, games and multimedia applications that can plug straight into any libretro-compatible frontend. This development interface is open to others so that they can run these pluggable emulator and game cores also in their own programs or devices.
Old x86 IBM PC emulator
Lakka is a lightweight Linux distribution that transforms a small computer into a full blown game console.
The Internet Arcade is a web-based library of arcade (coin-operated) video games from the 1970s through to the 1990s, emulated in JSMAME, part of the JSMESS software package. Containing hundreds of games ranging through many different genres and styles, the Arcade provides research, comparison, and entertainment in the realm of the Video Game Arcade.