Just how many Twitter followers and Facebook fans constitute a critical mass? Dan Zarrella, author of "The Social Media Marketing Book," says his Twitter account took off after the 2,000th follower, while his Facebook account found success after just 1,000 fans. Whom you follow matters too, he notes, adding that you shouldn't follow more people than follow you.
Virgin America devotes few people to Twitter and instead leverages its customers to keep others engaged with the brand through social media. Still, when it comes to customer-service issues, the company is actively monitoring and responding to the conversation.
Social-media tools are providing General Mills, Betty Crocker and other major CPG companies with the means to identify and access niche markets that once would have been considered too small to be profitable. General Mills recently added gluten-free baking products partly in response to online requests from customers.