Nestopia - A portable and cycle-accurate NES emulator written in C++
Roms Mania - A working online resource for roms.
Mesen - Mesen is a NES/Famicom emulator and NSF player.
Gamulator - Gamulator is the n.1 place to find and download all the retro roms, iso's and games for your arcade emulator.
FCEUX - FCEUX is a Nintendo Entertainment System (NES), Famicom, and Famicom Disk System (FDS) emulator.
CoolROM - Download from the largest and cleanest ROMs and emulators resource on the net. Mobile optimized. Systems include N64, GBA, SNES, NDS, GBC, NES, MAME, PSX, Gamecube and more.