DreamWorks and Paramount's comedy "Tropic Thunder" continued its reign at the No. 1 spot during the Labor Day weekend with a three-day haul of $11.5 million from 3,473 theaters. Ben Stiller’s "Tropic Thunder" dropped 29% in its third weekend, but has earned an estimated $83.8 million since its release. 20th Century Fox's new sci-fi/action flick "Babylon A.D." took the No. 2 spot with $9.7 million from 3,390, and showed that star Van Diesel can still draw a crowd. Even with “Tropic Thunder,” “Babylon A.D.,” and four other new movies in wide release, Variety reports the overall Labor Day traffic was slow. The final numbers for the four-day weekend won’t be released until today, but it looks to be down by about 14% from last year – which benefited from the remake of “Halloween.” The weekend heavy weights continued to be “Tropic Thunder” and Warner Bros.’ “The Dark Knight” – which crossed the $500 million mark on Sunday. "Dark Knight" continued to show its box office muscle with a decline of only 17% in its seventh weekend. The film earned $8.7 million from 2,750 runs. The film (which is now behind “Titanic” in its box office take) is expected to earn about $530 million domestically. Sony's comedy "The House Bunny" took the No. 4 spot in its second weekend, and dropped 43% with an estimated $8.3 million from 2,714. The film has earned $27.8 million since its release. Overture's political thriller “Traitor” (with Don Cheadle and Guy Pearce) had a solid opening with an estimated $7.9 million from 2,054 theaters through Sunday. The film took the No. 5 spot for the weekend. Lionsgate's spoof comedy "Disaster Movie" (which is another flick from the "Scary Movie" team) took the No. 7 spot with a three day opening that took in an estimated $6.2 million from 2,642 runs. MGM's comedy "College" managed to take the No. 15 spot with an estimated $2.1 million from 2,123 runs. Focus Features' "Hamlet 2" (which was picked up at Sundance) had a rough weekend with a No. 17 placing and an estimated $1.7 million take from 1,597 runs. The film has taken in $2.7 million since the limited release. Universal's "Mamma Mia!" saw a 2% bump during the holiday weekend with an estimated $4.4 million from 1,968 runs. The film has earned $131.5 million since its release. Universal re-released the film in a special “sing-along” edition in certain markets for the holiday weekend. Universal's remake of "Death Race" dropped 51% in its second weekend with only $6.2 million from 2,537 runs. The film has earned $23 million in its first 10 days. Woody Allen's "Vicky Cristina Barcelona" took the No. 10 spot for the weekend with an estimated $3 million from 692 runs. The film has earned $12.8 million since its release