Basilisk II - Basilisk II is an Open Source 68k Macintosh emulator.
FCEUX - FCEUX is a Nintendo Entertainment System (NES), Famicom, and Famicom Disk System (FDS) emulator.
Sheepshaver - Home page of the SheepShaver Macintosh emulator
Nestopia - A portable and cycle-accurate NES emulator written in C++
PCE - PCE is a collection of microcomputer emulators. At the moment it contains three emulators:
RetroArch - RetroArch is a frontend for emulators, game engines and media players.