If you've ever needed to control iTunes on another Mac over a local area network then TuneConnect could be your answer.
TuneConnect allows you to control your music simply, quickly, and easily, from anywhere on a network, so it doesn't really matter which machine your iTunes music is stored on. You can even scrobble your tracks to Last.fm, although this requires a separate file (available to download from the developer's site).
When you install TuneConnect, you also need to install the TuneConnect server on the machine that you want to control. You'll also need to activate Remote Apple Events on your own machine for communication to take place.
When you open it for the first time, TuneConnect searches for connected devices and then allows you to select which ones are available. Alternatively, you can enter a computer name or IP address, including the port access number to control iTunes on another machine.
Then you're ready to go. The tracks you're playing are displayed in the TuneConnect interface and you can perform all the basic control functions you would if you were using iTunes on your own machine. Some users have reported that TuneConnect has been disabled sometimes when iTunes updates, so if you are going to rely on it, bear this in mind the next time you update.
For anyone wanting to control iTunes on another network machines, TuneConnect is a simple and elegant solution.