Groupon built the online group coupon model and has led the way ever since. Along with its competitors the site offers discounts of 50-70 percent off goods and services at restaurants, retail stores, spas, and travel. What the other sites don't have is $1 billion in capital investment and a valuation of up to $25 billion. Groupon has increased from 4 million unique visitors per month last year to over 20 million this year but with LivingSocial closing the gap, Groupon will need to continue their growth to hold onto the lead.
Groupon.com/AP