MagentoShowcase
A gallery of beautifully designed Magento web sites.
EIO Clothing
High contrast fashion store. Magento is fairly transparent and the product pages feature some nice AJAX elements.
The Purveyor
Sellers of fine spirits and Champagne. The Purveyor makes use of a light on dark theme and have done a good job of making the use of Magento as transparent as possible.
In case you didn't know... Magento is a phenomenally powerfull, Open Source shopping cart application. MagentoShowcase.co.uk acts as a gallery, featuring aesthetically, or functionally inspiring web sites developed on the Magento platform.