I wanted to showcase/show off a store we just finished, it is based on nopcommerce 1.70. We introduced multiple images for each product variant and worked a lot on the product page layout. Each product variant is also related to a color variant attribute so that we could show multiple color images without postbacks using .NET update panels. We also generated the main menu from the product categories.
Working with nopcommerce was great, and I've learned a lot from looking at how this app is coded. It was a great experience for me.