Yelp is entering one of the hottest areas of the online economy. The business review site is buying online food ordering service Eat24 for $134 million. Eat24, which has been around for seven years, often uses edgy marketing to stand out from its competitors on social media and elsewhere. It also had rapper Snoop Dogg appear in its Super Bowl ad. Like other online food ordering services, Eat24 makes money by keeping a percentage of sales from restaurants. Yelp's acquisition puts it in direct competition with established players such as market leader GrubHub. Others in the space include Delivery.com, FoodtoEat.com and OrderUp.com. Yelp raised its revenue outlook for the current quarter and the full year.