Groupon's latest nationwide deal has a twist

The online daily-deal company launched a three-day nationwide deal for burgers, Friday through Sunday. The wrinkle? Instead of doing a deal with a big fast-food chain like McDonald's Corp. or Burger King Corp., Groupon signed up more than 350 restaurants across the country, from Duke's Bar & Grill at 2616 N. Clark St. in Chicago to Mel's Diner in San Francisco.

The burger promotion is one of several experiments Groupon has launched recently as it tests what else it can do with its business of coupon-based advertising for merchants.

The Chicago-based company, widely expected to launch an initial public offering later this year, is the leader in the young industry with more than 70 million e-mail subscribers. Since launching in late 2008, it virtually created a new advertising business in which local merchants offer big discounts to deal-hungry consumers, splitting the take with Groupon.

Groupon has demonstrated appeal to businesses ranging from mom-and-pop shops to national retailers such as Gap Inc., but it's not clear which market the company will pursue, or both. As the space quickly evolves, attracting local copycats and larger rivals such a LivingSocial.com and Internet-advertising giant Google Inc., Groupon is testing different combinations of deals and technologies and strategies in hopes of remaining the dominant player.

Last week, the company launched GrouponNow, a product that allows businesses to offer time-limited deals to customers nearby instead of open-ended offers in a single e-mail blast.

Last month, it started Groupon Channels, separate deals in specific categories, such as home and garden that are aimed at subscribers based on buying habits which is more targeted than its general e-mail blast. The company then created a joint venture with concert giant LiveNation Entertainment Inc. to offer discounted tickets for shows that are slow to sell out.

Recently, Groupon launched a deal with Quizno's, the Denver-based sandwich chain, which offered half-off discounts on punch cards at more than 2,000 locations nationwide.