There may be a lot of economic uncertainty, but that doesn't mean it's a bad time to launch a business. For a few business ideas, take a spin through this list of eight online industries expected to see healthy U.S. revenue growth in 2013 that are hot for startups, according to industry research firm IBISWorld.

Social network game development -- People are spending more time on social networks like Facebook and they are also spending an ever increasing number of hours online, thanks to the rapid adoption of mobile devices like smartphones and tablets. Consumers are spending more time playing games that are embedded into their social network: The industry has grown by an astonishing 184 percent per year on average for the past five years, IBIS reports. By the end of 2013, U.S. sales in the industry are expected to grow another 32 percent and hit $6 billion.

Online shoe sales -- What woman can’t find an excuse for why she absolutely needs another pair of shoes? Couple that with a surge in ecommerce, and U.S. online shoe sales have grown by more than 16 percent per year on average over the past five years and the industry is predicted to near $9 billion in U.S. revenue in 2013. While there are already some big players in the market, Amazon.com which owns Zappos.com and FootLocker.com make up only 16 percent of the industry. Without a juggernaut in the industry, there is room for startups, IBISWorld says, but make sure to have your own special spin on shoes.

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