|Why They're Hot:
A large portion of PetFlow.com's site visitors—around 30%, in fact—come from Facebook. Its fans love the constant stream of images the merchant posts of cute animals and funny taglines, says co-founder Alex Zhardanovsky. But when consumers actually click to the site from Facebook, it's often from a link for a deeply discounted item. So, in an effort to turn fans into buyers, the merchant heavily touts discounts on its home page and landing pages. A clock counts down the hour and minute when the merchant's deals reset, for example, and tiled product images feature bright red banners listing each discount—43% off, 61% off or more. An Add to Cart button attached to a selection of products takes shoppers quickly from home page to checkout.