Amazon has introduced a new ad platform for mobile app developers, as part of the company’s effort to take on Google and Facebook in the rapidly growing smartphone advertising market. “The service lets developers promote their apps on Android smartphones and tablets as well as Amazon tablets, paying Amazon each time a user clicks an advertisement displayed through the system,” notes Bloomberg. “Campaigns start at $100.” According to eMarketer, Amazon currently has less than a 1 percent share of the $28.7 billion U.S. mobile ad market, while Google dominates at 35 percent and Facebook maintains 17 percent.