Every CMS needs a theme. You can start with someone else's theme to get started, and then you can (and should) create your own.

Here are a few places to get and learn about XOOPS themes:

• XOOPS Theme Repository
• XOOPS Themes News
• XOOPS Theme Development Tutorial

Here are some sites that have themes:

• ThemeBot (also themes for other CMSes that could be adapted with a little effort)
• MrThemes (requires registration)

Building your own theme isn't hard. I find it easiest to develop a standard HTML template laying everything out using your favorite designer from a content standpoint. Just make sure you design the blocks and such. Then it's really easy to cut it up and make your own theme by putting the code into the proper theme receptacles.

I also suggest that any stylesheets (*.css) files in the module be moved to the theme's stylesheet so that you have better control over each theme you allow your users to choose.