Here are some custom Winamp Skins that you can download and use for the MP3 Player:

Winamp Skin 1 (38 KB)
Winamp Skin 2 (64 KB)
Winamp Skin 3 (151 KB)
Winamp Skin 4 (45 KB)
Winamp Skin 5 (227 KB)
Winamp Skin 6 (84 KB)
Winamp Skin 7 (155 KB)
Winamp Skin 8 (257 KB)

To install the files, download and unzip into the 'Winamp' -> 'Skins' Folder.  Then you can go into winamp and choose the skin.