After several weeks of unloading summer tentpoles to varying degrees of success, this weekend brings a clutch of films with more specialized appeal. Hoping to continue a trend of strong performances for adult fare, Universal is debuting “Cinderella Man” at 2,812 theaters today. Sony unspools the 1970s skateboard movie “Lords of Dogtown,” which is strongest with teens, at 1,865. On Wednesday, Warner Bros. launched the weekend’s widest new release, young femme-friendly “Sisterhood of the Traveling Pants,” at 3,583 venues and saw first-day results of $2.1 million. New arrivals may have a tough time displacing the holdovers at the top of the box office chart. Finishes in the $20 million-$30 million neighborhood are likely for the third week of 20th Century Fox’s “Star Wars: Episode III — Revenge of the Sith” and the second-week sessions of DreamWorks’ “Madagascar” and Paramount’s “The Longest Yard.” “Cinderella Man,” starring Russell Crowe, helmed by Ron Howard and produced by Brian Grazer, has the best shot at the box office title. It’s the latest attempt at counterprogramming a prestige title during the summer’s typically light fare.