Karaokii is just what its name says: a Karaoke for Wii. It shows the lyrics from the song is playing by following the rhythm of the music. All files must be stored under /apps/Karaokii/songs/ in a SD card readable by Wii. Music comes always in OGG format, although mod or mp3 support could be added in the future. Karaokii features two kinds of lyrics: 'line karaoke' and 'word karaoke'. It can read 'Ultrastar', 'Ultrastar-ng', 'Ultrastar deluxe' and 'Performous' lyrics files by renaming their extension to '.ki3'. All '.kii', '.ki2' and '.ki3' can be 'image-scripted' to show animations while song playing. Sorry about no voice recognizing by the moment ;), there are no microphone libraries yet.

• Wii Homebrew: Wii Game Studio
• Wii homebrew - BlueMSX-wii v1.0
  

Via Wiibrew