Nintendo Emulators
Super Nintendo Emulators
ZNES- One of the best Super Nintendo emulators available. Initially DOS only, but now also for Windows.
Snes9x- Great Super Nintendo emulator with ports available for several systems.
NES Emulators
Nestopia- NES Emulator
Jnes- Another good NES emulator for Windows. Requires a reasonbly fast PC.
FCEUX- Back again, now open source, ported for Windows and much improved!
Nintendo 64 Emulators
Project64- One of the best Nintendo 64 emulators available.