Ports of Nestopia:

Nestopia Linux (Arbee)
Nestopia Mac OS (Richard Bannister)
OpenNestopia Mac OS (Daemoncollector)

Translations of Nestopia:

French (Benjamin Siskoo)
Japanese (Nekokabu)

Other NES emulators:

Mednafen
Nessie
Nintendulator
VirtuaNES