It was the customer service screwup heard around the world. In 2009, Canadian musician Dave Carroll became an overnight YouTube star with a music video called "United Breaks Guitars." It told the story of how United Airlines refused to compensate Carroll after baggage handlers smashed his $3,500 guitar. In four days, the video received one million hits.

Last year, Carroll parlayed his YouTube fame into a start-up called Gripevine, a website that lets customers air complaints about businesses. Now, Carroll hopes to finally start earning revenue by helping businesses appease unhappy customers before they become social-media stars. Resolution 1, his new customer service platform, monitors feedback on social media and other sites. The tool also tracks the performance of customer reps and analyzes complaint volume by region. Prices start at $10 a month per company.

Carroll says launching a business has made him realize how hard it is to keep customers happy. "I can totally understand how feedback can get out of hand for a big operation like an airline," he says. "Hopefully, this tool will make everyone's lives easier."