Created by Mirabilis and bought out by America Online, ICQ is a very popular instant message/chat program that lets you keep in touch with your friends when they get online. It's free, over 90 million internet users worldwide are registered.
If you don't like the standard interface, you can now change it around with a little add-on program called ICQ Plus. This program allows you to "skin" the program with alternative images. There are many available around the internet, including the celebrity related ones listed on Celebrity Desktop.
If you already have the ICQ program, then just visit the ICQ Plus web site and download this free add-on. A little + icon should appear in your ICQ program next time it starts up. Clicking on that will bring up a list of skins you have available. You can also click the ICQ's main button to bring up the menu. In there should be a yellow + Plus icon, which will bring up the plus window. From there, you can import all the skins you've downloaded, preview, and even edit them. That's all there is to it!
If you're interested in creating your own ICQ skins, then just use the program to create a "new" skin, and edit in your own images and button files. When you're done, click the Export button to save it as a zip file. Upload that file on the web if you'd like to share it with others.