Not long after Balter got the big news that BzzAgent had landed $13.8 million in venture capital financing, he zipped me an email. “I have this crazy idea,” he said. “I want you to come in and hang out at the office for three months. Let’s have coffee and talk about it.”

We met one Sunday morning in January at Peet’s in Harvard Square. “We’re changing our whole business model,” Balter said. “We’re going to go from 45 people to 80 by December. We’re gonna double our sales next year. I want you to write about it.”

“We’ve already written about it,” I said. Grapevine, the book about word-of-mouth that we co-authored, was published in October 2005.

“This’ll be different,” he said, and gleamed at me. That’s what Balter does when he gets hold of an idea. He gleams. “It’ll be a social experiment. I don’t know what will happen. It’ll be fascinating. Besides, you need a sabbatical.”

“True,” I said. I had written three books in thirteen months.

“Good,” he said. “When can you start?”