Mac (Mountain Lion): If you shuffle a lot of music all day long in iTunes or Spotify, it's easy to lose track of what's playing at any given moment. If you're running Mountain Lion, iTunification is a free app that sends the currently playing track directly to your Notification Center.
With iTunification installed, you get a quick notification when a new song starts in the native Notification Center. You can also set up a silent mode where it doesn't send notifications, or you can customise its alert behaviour in the System Preferences. It's a simple little tool, but if you like to see popups when a new song plays, iTunification is handy to have around. You can download iTunification for free from the developer's site below.