Are you looking for free Multiply themes or free Multiply layouts for your Multiply site? Then here is a blog/site that might help you. Multiply Themes and Layouts is a great collection of customized CSS codes, backgrounds that you can use for your Multiply layout.
You'll see a lot of simple, colorful and animated themes there. There's also a tutorial on how to animate the headshot in multiply (animated GIF headshot).
Here's an example of theme, Twilight Multiply theme from the website:
Here's the link that will bring you to this Twilight Multiply theme customized CSS codes.
Go ahead and visit the Multiply Themes and Layouts website. Enjoy!