Quicky is a great but simple app to let you control iTunes as easily as possible. It is placed in your Mac's status bar, and when you click on its icon, it will show a nice little menu with a play/pause button and skip and scrub buttons.
Have a look at the screenshot! The advantage of Quicky is that you can access it quickly no matter what you are currently doing - the status bar is always there! In this vein, Quicky is a great tool for Mac users who listen to music to iTunes when they are working and do not want to switch to iTunes to play the next song!