When Los Angeles-based attorney Steve Weinberg got two referrals through LinkedIn, he was intrigued. Like many attorneys and other professional services providers, he’d had a LinkedIn page for years. But when one of the referrals turned into a piece of business, Weinberg was sold.

The fact is that businesses largely dependent on lead generation are thriving online. Legal and accounting services are poised to be the next big marketplaces and will likely surpass insurance and other financial services on the web. The key? Social media, and the numbers are staggering. LinkedIn alone has more than 75 million profiles. Sixty percent of all Americans use social media at least once a week and 80 percent at least once a month. We’re tweeting more than a billion times a month, and the number of page views for social media sites grab a larger percentage of time spent online, with estimates at 10 to 25 percent of Internet usage and doubling each year.