I would to share with you our Norwegian flash sales site, www.brandsonly.no, developed on nopcommerce.
The business model is to sell surplus goods from leading brands at 50-80% discount in time limited sales lasting from 2-21 days. The sales are only available to registered members.
The implementation is a bit different from traditional websites as each sales is focused around a brand (e.g Ralph Lauren) and that the sales are time limited. Also each sale needed to have subcategories (e.g. Men, Women, Shirts, pants etc). To achieve this we used the categories functionality of Nopcommerce, but added a "private sales" modules that control how long a sale is open, and also to insert appropriate logos and images for the sales graphics on the landing page/home page.
Another issue with flash sales is that all quantities are time limited and sell out fast. So if we only have 5 items of a product we did not want to risk our members to add this to the cart and then experience at checkout that the item is not available anymore. To fix this we changed the stock control of nopcommerce so that it deducts from stock when a member add to the cart. The member have 30 minutes to complete the shopping before the cart is deleted (they get a popup warning 5 minutes before) and the item is available for other members to buy.
For marketing purposes we needed to implement a functionality that allowed members to invite a friend and they would get NOK 50 when a friend who had registered based on their invitation made a purchase. To achieve this we developed a "share with friend" module in combination with the existing reward points functionality.
As the majority of our products are clothing we also needed a more efficient way to import and maintain inventory attributes for sizes (e.g. Large, medium , 50, 52, 54 etc). The default method setting inventory attributes is a bit labor intensive and also NopAdmin was too much work. To make this easier for us we developed a new excel import functionality that simply imports SKU, Attribute and Inventory (3 columns). We only have one inventory attribute per product.
As a lot of our products get sold out we needed to make it easier for customers to quickly find their products. E.g. if you use medium size, you should only view the medium size products with inventory available. Existing product filters (plugins) do not take into account inventory availability, so we needed to develop this one as well. Our filter is currently a bit slow, but we are working to improve the speed.
Hope you like it, and we appreciate feedback and comments.