RetroArch is a frontend for emulators, game engines and media players.
Virtualization software for x86_64 hardware
Versatile Commodore Emulator
Run Windows applications on Linux, BSD, Solaris, and Mac OS X
Unix system man page on the web
Create your own Atari tapes
JavaScript framework to build game engines, games, emulators and apps
Cluster administration tool
z390 Portable Mainframe Assembler and Emulator
Twin is a "retro" program for embedded or remote systems