Marc Lore and Vinit Bharara have figured out a formula for selling low-margin goods online and shipping them overnight to customers. The two entrepreneurs have built Diapers.com into the largest seller of diapers and other baby products on the Web. Diapers.com is on track to bring in $300 million in revenues this year. Now the two are getting ready to launch a new e-commerce site, Soap.com. . It will sell much more than just soap. When it launches in July, Soap.com will offer 25,000 products—daily essentials ranging from cleaning supplies to toothpaste. By the end of the year, it will offer 60,000 different products, all at the same price you'll find at Target or Wal-Mart, and about 25 percent less than at a typical drugstore, with free overnight shipping for orders of $50 or more. The overnight shipping is key because when you run out of toilet paper you can't really wait around three days for your order to arrive.