The built-in visualization capabilities of Winamp are impressive by themselves, but if you want to go a level beyond and watch your music really dance, Winamp's support for plug-ins is the key to your dreams. The Plug-ins section of the Winamp Web site features tons of plug-ins from windowed and full-screen visualization plug-ins to input and output plug-ins for enhancing Winamp's audio capabilities.
The plug-ins are updated regularly, so be sure to check the site for the latest releases. Regardless of whether you decide to go with the built-in visualization tools or one of the many plug-ins, Winamp offers some serious 'candy for the eyes' to go along with its excellent audio capabilities.
Another cool customization feature is Winamp's support for skins. Skins are custom designed interfaces that slip over the default Winamp interface. Skins retain the same set of features as the default interface; they only change the look and feel of the interface. You can create your own skins or download from the hundreds of skins available in the Skins section of the Winamp Web site.