Gap’s 50%-discount offered on the collective-buying site Groupon last week rang up a reported $11 million in sales, says ClickZ, and in the process demonstrated some best practices for ecommerce in this new, more social Web 2.0 era.

According to Groupon spokesperson Julie Mossler, the Gap offer was the most successful Groupon promotion to date, ringing up as many as 532 transactions per minute during its busiest periods Thursday morning. Traffic was so intense that Groupon had to manage the load by directing visitors to alternate landing pages in order to avert a server crash.

What I find impressive about the Gap campaign is the sheer number of coordinated moving parts cross-promoting a single offer:

  • 15 million Gap and Groupon email subscribers receive the offer, starting at midnight and in staggered fashion throughout the day
  • The offer is tweeted to the 180,000+ followers of Twitter’s @earlybird promoted tweet stream
  • Gap tweets the offer to its 30,000+ followers
  • Groupon manually tweets and Facebook posts on its pages dedicated to each of the 85 geographical markets where Gap’s offer is valid
  • Gap posts the offer to its 606,000 fans on Facebook
  • Groupon’s 1,500 affiliate partners post Gap’s offer on their websites
  • A sponsored post appears above the fold on Digg

All in all, it sounds like a big win for Gap, and impressive evidence of how online promotion and social shopping, courtesy of Groupon, can drive sales to brick and mortar stores.

“Our customers had been asking us to feature a national retailer, and the Gap deal was a perfect fit for Back-To-School and even pre-holiday shopping,” Mossler explained. “Gap even has stores where Groupon hasn’t launched yet; so, it’s a perfect way to reach new and existing Groupon fans with a deal they won’t find anywhere else.”