Shopping at home, while lacking that personal touch of a brick and mortar store, is extremely convenient and is becoming extremely popular. The growth in online sales has made huge leaps and bounds this year, with a whopping 25% increase over last year. With more and more retailers offering web-based sales and many companies existing solely on Internet sales (such as Newegg), it's no wonder that it's growing. On top of just growing, however, it's extending the traditional “holiday shopping” out further than normal. Rather than huge spikes and then huge dips, companies are seeing more steady traffic longer into the end of the year. Online-only retailers have been especially happy:

Nielsen/NetRatings also noted that the number of visits to online-only retailers this season has been 54 percent greater than visits to those with both online and brick-and-mortar offerings. Still, visits to those with both offerings have increased 21 percent year over year, while visits to online-only retailers have increased 12 percent, Nielsen/Net Ratings said.
Personally, I buy online primarily because of how much cheaper things tend to be. The price difference between a 100 pack of DVDs on a store shelf versus the same 100 pack at an online retailer is often more than worth the time it takes to have it shipped.