Zune Lyrics is a plug-in for Zune Software which automatically fetches lyrics of the song currently being played in Zune Software from lyricwiki.org. Built using WPF, it uses the registry data stored by Zune – Now Playing to detect the current song.
You can find Zune – Now Playing at http://znp.codeplex.com

Download the zip file and run Setup.exe. Follow the instructions to install Zune Lyrics on your system. Run Zune Lyrics from your desktop or Programs Menu