Have you guys seen the "mini lyrics" app for windows? It downloads the lyrics of the currently playing song and displays it on the screen. The great thing about it is that it highlights the current part of the lyrics. Do you know any alternative of it for mac?
I use this. It will display the lyrics and add them to your iTunes library (if you choose to) I would highly recommend it.
There is also LessLyrics. I haven't used it before.