c64-network.org is a Commodore 64 emulator written by Christian Bauer (http://frodo.cebix.net). It was ported to the Wii by Simon Kagstrom, and many C64 games are fully playable on the Wii with it. So go ahead and beat your friends in International Karate, Boulder Dash or Bomb Jack. This version is not the same as Troy Davis implementation, but Troys work is available in a branch in the subversion tree.
The emulator works best in 480i and 480p mode. It runs perfectly fine in 576i mode as well, but does not utilize the full resolution. This is an SDL issue, and will not be fixed until SDL-Port supports it. The emulation itself is not perfect, so not all games will run under Frodo. Unfortunately, I cannot do very much about this since I haven't written the emulator - just ported it. If you have multiple versions of a game, try each of them as often at least one will work.