We all sing-a-long to our favorite songs. Maybe it's in the car. Maybe it's in the shower. Maybe it's at your company's karaoke party and you're trying your best to sing Once Bitten, Twice Shy even though you don't really like the song. Wherever you're singing, there's a good chance you're singing it wrong. Here's an app that'll fix that and save you from the occasional "Hold me closer, Tony Danza."