4. Peer-to-Peer Lending Platforms

Peer-to-peer lending platforms revenues grew at an annualized rate of nearly 60% from 2009 through 2014. While growth is expected to slow somewhat, it should remain strong in the years to come, according to IBISWorld. Most recently, one of the major players in the growing industry, Lending Club, successfully completed the industry’s first initial public offering. However, the peer-to-peer name itself is something of a misnomer, with institutional investors offering a large portion of the loans provided. Recently, Wall Street has begun securitizing peer-to-peer loans, creating a secondary market for institutional clients.

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3. Social Network Game Development

Social network site users do not just interact with others online. They also view advertising, navigate to other online spaces, and play games. Social network games have a remarkably high user base, which has been estimated in the hundreds of millions of people on a monthly basis in recent years. The social network games industry brought in more than $7.9 billion this year, according to IBISWorld. According to online statistics provider Statista, social gaming ads accounted for 7.4% of all ad revenue for social networks.

2. Crowdsourcing Service Providers

Crowdsourcing is a relatively new workforce model that connects employers with temporary workers through an online network. Crowdsourcing service providers increased revenue at an annualized rate of 62.6% since 2009 to a total of nearly $543 billion this year. Like a majority of growing industries, the popularity of the crowdsource model is tied to the now near-ubiquity of the Internet. According to IBISWorld, crowdsourced temp employees typically work online and on a project-to-project basis.

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1. Solar Power

Solar has grown exponentially in recent years, with an annualized growth rate of 70% between 2009 and 2014 — faster revenue growth than that of any other industry. A dramatic drop in the cost of solar photovoltaic systems — panels that convert sunlight into electricity — has encouraged utility companies to dramatically increase installations in recent years. In the first half of 2014, power plants added more capacity from solar power than from any other energy source except for natural gas, according to the Energy Information Administration. Photovoltaic installations rose 41% year-over-year in the third quarter of 2014, according to the Solar Energy Industries Association. The International Energy Agency reported in September that solar could, with the right policy actions and technological improvements, become the world’s largest source of electricity by 2050.