1. MAC cosmetics, by Jessie Tettemer
Facebook fans (on July 1): 3.5 million
Twitter followers (in July): 51,000
"Our followers always ask, 'What one thing from MAC do I need?' That's like asking me to pick a favorite child. But if I open it up to the crowd, responses come in from around the world."
2. Ring Pop, by Wendi Leggitt and Dana Wickrowski
Facebook fans: 271,000
Wickrowski: "We've got this huge fan base of young and enthusiastic girls, so we keep it age appropriate by asking silly stuff like, What's your secret talent?"
3. American Express, by Matthew Burton and Amy Tokarski
Facebook fans: 2.5 million
Twitter followers: 535,000
Burton: "You wonder what makes people want to interact with businesses. For us, it's membership. People tweet that they're excited about getting their card."
American Express on Twitter 
Matthew Burton on Twitter 
Amy Tokarski on Twitter 
4. Starwood Preferred Guest, by Carrie Houston and Rebecca McCullough
Facebook fans: 115,000
Twitter followers: 22,000
McCullough: "A guest tweeted that he took the coffee from his room because he loved it so much. So for his next stay, we covered his room in coffee packets.He tweeted back, 'What would you do if I said I wanted an iPad?'"
5. Hornitos, by Chris Black
Facebook fans: 270,000
"Our page is about the tequila, but it's also about events and exploring cities. Right now, I'm headed to San Diego for the world championship for dog surfing. Hopefully, we'll get some great photos of dogs in wet suits." (The company is in Illinois, but Black operates from his Brooklyn, New York, apartment.)
Hornitos on Facebook 
6. Goldman Sachs, by Jake Siewert
Facebook fans: 20,000
Twitter followers: 16,000
"Even the Federal Reserve, a staid organization, is using Twitter to communicate and find utility. We just couldn't not be in the space."
7. HBO, by Lindsey Pearl and Jim Marsh
Facebook fans: 7.8 million
Twitter followers: 374,000
Pearl: "When Denis O'Hare's character on True Blood, Russell Edgington, rips out the newscaster's spine on live TV, that was the gift that keeps on giving."
8. Brooklyn Nets, by Kristen Baier and Jayne Bussman-Wise
Facebook fans: 278,000
Twitter followers: 119,000
Bussman-Wise: "I grew up in New Jersey following the Nets and have lived in Brooklyn for eight years. So for me it's a perfect fit. I'll think of where I'm from. A lot of our messaging is about transportation, so people know how to get here from tunnel."
9. Yahoo Finance, by Stacy Curtin, Kensey Lamb, Caroline Kim, and Ross Tucker
Facebook fans: 236,000
Twitter followers: 115,000
Curtin: "The Facebook IPO was a watershed moment for both us and our social media users because they were so addicted to real-time information. It's a huge rush."
10. Pfizer, by Jennifer Kokell
Facebook fans: 56,000
Twitter followers: 30,000
"When we created our page, we had to tweet that we were the official Pfizer, because we got push back from bloggers who didn't believe we were the real thing. Finally, we called bloggers directly saying, 'This is us, we're for real.'"
11. Etsy, by Laura Chin
Facebook fans: 844,000
Twitter followers: 1.7 million
"During wedding season, we had one buyer who tweeted that she was looking for a vintage wedding dress just like her grandmother's. We saw it and were able to help her find the right dress."
12. Museum of Modern Art, New York, by Victor Samra
Facebook fans: 1.1 million
Twitter followers: 1.1 million
"I think of talking to our fans as if I'm meeting a friend's relative who may not know much about art but wants to learn something about it."