You can now make your own!
Here is a Studio Ghibli one I made. I haven't submitted to google yet. Need to change a few more things. But you can use it now by using this link
It changed about every 2 hours except from 12am - 4am & 8pm - midnight. I may change this up later.
http://www.google.com/ig?skin=http:/...udioGhibli.xml
http://code.google.com/apis/themes/docs/dev_guide.html