nopCommerce online store now can have this features by using this plugin.
You will see a countdown displayed on top of product images.
Just simply install plugin, and：
1. specify widget zone you want to display to;
2. Number of product you want to display;
3. image size;
4. set your discount on product detail page;
5. then go to your widget management page, activate this widget, and it's done.
this plugin is available for nopCommerce 2.6, 2.7 and 2.8.
for more details, please see here - http://www.nopcommerce.net/nopcommerce-deal-of-the-day
