Here's a site I built using the Ubercart and the Acquia Slate theme from Top Notch Themes: www.caldwellpics.com

I'm not using the Ubercart Catalog but rather a custom Catalog built with Views and Taxonomy. Seems to work a bit better and I have much more control over it. I modified the Acquia Slate theme with UberCart specific CSS so it works together nicely (since Acquia Slate isn't a UberCart theme by default).