RetroArch is a frontend for emulators, game engines and media players.
An advanced network simulator to design and configure virtual networks
Versatile Commodore Emulator
Run Windows applications on Linux, BSD, Solaris, and Mac OS X
C64/Amiga emulator with shader and runAhead
C64 Emulator
a multiplatform, full-featured GameBoy classic emulator
Emulator of the 8-bit computers Sharp MZ-800 / MZ-700
Эмулятор ЭКВМ серии «Электроника»
Z80 shared library including some nice test-projects
Create your own Atari tapes