A few days after Yahoo announced it would lay off nearly 700 workers, Yahoo is shutting down GeoCities, which it acquired in 1999 for $4 billion. GeoCities is the latest casualty in Chief Executive Carol Bartz’s campaign to close duplicative and underperforming products. Last week, Yahoo announced the closing of Jumpcut, an online video-editing service, and FareChase, a travel Web site. During Yahoo’s earnings call on Tuesday, Bartz also mentioned the discontinuation of Yahoo Briefcase, My Web, Yahoo Audio Search,