The snowstorm that walloped the East Coast over the weekend hit retailers hard, forcing store closures and keeping shoppers at home by the fire. But those heavy storm clouds had a silver lining for shippers like United Parcel Service, the world's largest package delivery company, whose business peaks annually with the global gift-giving frenzy that culminates around Christmastime. On Monday, UPS' busiest day of the year, the company delivered 22 million packages. Wednesday it will deliver 6 million more by air.

To be sure, the weekend's weather made driving and flying more difficult UPS' drivers and pilots. But as they cool their heels back at the hubs, waiting out the weather, they knew the work would be there for them when the skies cleared.

In fact, the increase in online shopping, which has turned out to be a sweet spot in an otherwise underwhelming holiday spending season, has been a real boon to shippers. UPS rival FedEx, which shipped 14 million packages on its busiest day earlier this month - 2 million more than last year - says much of this year's spike in volume tracks the rising popularity of holiday e-tailing among busy consumers.

Those trends mesh with data from tracking firm Coremetrics, which found that although online sales usually drop off before Christmas as free shipping incentives end, this year is different. Online buying started to surge on Friday afternoon and continued over the weekend. Sales for Friday and Saturday were up 24 percent year-over-year; sales for Sunday were up 20 percent.

Clearly, snowbound shoppers who couldn't make it out to the malls still managed to tick items off their Christmas lists by firing up their computers and hopping online to shop. UPS ships their packages either way, so for them, the weekend's winter weather was a win-win.