Basilisk II - Basilisk II is an Open Source 68k Macintosh emulator.
Stella - Stella is a multi-platform Atari 2600 VCS emulator released under the GNU General Public License...
Sheepshaver - Home page of the SheepShaver Macintosh emulator
WinUAE - WinUAE is a Windows port of the emulator UAE.
PCE - PCE is a collection of microcomputer emulators. At the moment it contains three emulators:
jGameBase - jGameBase is a fully-featured retro-gaming emulator frontend and game database utility.