Stella - Stella is a multi-platform Atari 2600 VCS emulator released under the GNU General Public License...
WinUAE - WinUAE is a Windows port of the emulator UAE.
Amiga Forever - The official Amiga preservation, emulation and support suite with games, demoscene, history and culture.
jGameBase - jGameBase is a fully-featured retro-gaming emulator frontend and game database utility.
Amikit - AmiKit turns your computer into legendary Amiga.
Z26 - Z26 is one of the best emulators for the Atari 2600.