Found this in a weekly list-of-links I subscribe to called the Scout Report:
MiniLyrics is a plug-in that works with RealOne, Windows Media Player, WinAmp, Music Match Jukebox, and most other well-known music players. When you play a song, MiniLyrics comes up and displays the lyrics, following the song line by line. Just downloaded it and tried it out to “House of the Rising Sun” by the Animals, and it worked perfectly. Free and worth a download!