The MacGIMP project has just posted a themes page.
See this link: http://www.macgimp.org/gimpshots
It has pictures of about 15 window manager themes that work on Mac OS X.
Very cool.
I'm thinking of installing XDarwin and would like to hear any stories, pro or con, about whether the XDarwin 1.0a1 is worth installing. Also, how difficult is it to get working? How long did it take you? Is this a ten minutes project or a ten hours project?