Hi
I'm a MoinMoin user - I help run http://www.mythtv.info/
I think I've created a fairly good look for the site - only CSS but uses 'fixed' css to get a frames feel. It also works on IE5/IE6/Moz and Firefox 
Must put it on the ThemeMarket...
I'm interested in the Themes support at the moment (May 05) and I'm trying to hack through the Python to add some css tags to the search page results...
I found a bug to do with Moin's caching and reported it here: MoinMoinBugs/CacheThemeConflict
I'd also like to see some discussion about css support... I created this: MoinMoinTodo/SkinPlugins/ThemeCssSpecification