Frodo 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. It does not share any code with FrodoWii, but would be happy to integrate improvements from it!
The emulator works best in 480i 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. Sound support is slightly buggy, but usable. The emulation itself is not perfect, so not all games will not run under Frodo.