I've yet to find a music/lyrics app that isn't half-broken or riddled with spyware and advertising. Edit: I thought saying "app" made it clear I needed it for a mobile device, Android, sorry. Foobar2000 is my choice of music player, it just doesn't do lyrics on mobile. I do think it's a testament to how underserved this niche is that all the replies are either desktop programs or mobile apps that don't support displaying lyrics while playing a song.