Bryce Gruber is the 23-year-old owner of IntenCity Global, a five-person marketing and public-relations firm in New York. She says Facebook works well for her and has brought tangible results. She recently drew more than 300 people to an opening party for a clothing store that she expected would only attract 150 to 200. And the people who learned of the party through Facebook bought several thousand dollars in merchandise. Her approach is to post information and reminders about her events regularly, and upload plenty of party pictures afterward. Each day, she gets 20 to 30 messages on her Wall and keeps that going with quick replies. The effort means she shows up often in her Facebook friends’ news feeds, where people are notified of their friend’s activities on Facebook.