It's easy to change your itunes skins. Many itunes skins for Windows and Mac are included on this page. Click the provided links to download itunes skins, or search internet for more.
Thanks to Davi's great work, so many iTunes skins are created by this designer on DeviantART website. And the last iTunes skin is designed by Masaliukas. Click the link to view more information about the itunes skin and click the button in the top right corner to download. All skins support iTunes 10.1 to iTunes 10.5.
There are less itunes skins for Mac provided here, but the latest iTunes 10.7 already included.
iTunes skin compatible with 10.7:
iTunes skin compatible with 10.6:http://killaaaron.deviantart.com/art/Nuala-iTunes-10-For-OS-X-177754764
iTunes skin for 10.1 to 10.6:http://marsmuse.deviantart.com/art/Crystal-Black-iTunes-10-186560519
iTunes skin for 10.0.1 and 10.1 ONLY: http://jaj43123.deviantart.com/art/Genuine-iTunes-10-To-8-178094032
Generally, double click on the EXE (Windows itunes skins) or DMG (Mac itunes skins) file to install. For some iTunes skins, you only need to replace the original iTunes.rsrc with the newly downloaded one. But you MUST backup the original file before replacement. Revert to the original iTunes.rsrc file before you update iTunes application. Here is the default path to iTunes.rsrc: /Applications/iTunes.app/Contents/Resources/iTunes.rsrc
NOTICE: All copy rights belongs to the original designers. Take your own risk to use these itunes skins. They are provided as-it-is.