FCE Ultra GX is a modified port of FCE Ultra v0.98.12. With it you can play NES games on your Wii/GameCube. The GUI is powered by libwiigui.

Features:

Wiimote, Nunchuk, Classic, and Gamecube controller support
iNES, FDS, VS, UNIF, and NSF ROM support
1-4 Player support
Zapper support
RAM / State saving support
Custom controller configurations
SD, USB, DVD, SMB, Zip, and 7z support
Cheat support (.CHT files)
IPS/UPS/PPF automatic patching support
NES Compatibility Based on FCEUX 2.1.2

Changes:

[3.1.3 – December 23, 2009]
* Fixed major file loading issue, more games load now
* File browser now scrolls down to the last game when returning to browser
* Auto update for those using USB now works
* Fixed scrollbar up/down buttons
* Fixed zapper
* Updates from FCEUX
* Minor optimizations

Free and legal NES roms to try with this emulator can be downloaded from here: http://www.pdroms.de/files/nes/

Source: http://www.wiibrew.org/wiki/FCE_Ultra_GX

http://code.google.com/p/fceugc/