My iTunes library has grow fairly large over the years and contains many songs I don't recognize. After entering a few simple Terminal commands, I now get a notification above the iTunes icon in the Dock with artist and track info when a song starts.
If this sounds like something you might be interested in, open up Terminal and enter these three commands:
defaults write com.apple.dock itunes-notifications -bool TRUE
defaults write com.apple.dock notification-always-show-image -bool TRUE
(The first command adds the artist and track information, and the second command adds the iTunes logo to the notification. If you don't care about the logo, you can skip the second command. The third command is akin to hitting Enter.)
Now, when you play a song in iTunes, a notification will pop up for a few seconds above the iTunes icon in the Dock, showing artist and track info. It works whether or not you have your Dock hidden, and on hidden Docks, it displays the notification without showing the Dock.
If you decide you don't like being shown such information, you can remove this notification by entering three similar commands in Terminal:
defaults delete com.apple.dock itunes-notifications
defaults delete com.apple.dock notification-always-show-image
In related news, if you'd like to add a small control to the menu bar on your Mac that works with iTunes, Spotify,and Rdio, I cannot recommend Skip Tunes highly enough. It allows quick access to artist, track, and album information while also providing play/pause, fast-forward, and rewind buttons.