The Smashing Pumpkins and ABBA are hot on itunes due to songs from "Watchmen" and "Mama Mia" movies.

Rolling Stone:

The Smashing Pumpkins 1997 tune “The Beginning is the End is the Beginning” has found a new life thanks to the upcoming Watchmen movie. Since it appeared in trailers for the film version of the cult graphic novel, “Beginning” is the number one most downloaded Pumpkins song on iTunes, and is one of the top forty most popular tracks overall. Interestingly, this is not the first time the song has been in a comic book movie as “Beginning” was originally released on the Batman and Robin soundtrack. On the other side of the music spectrum, Abba is getting a boost in record sales thanks to the new Mamma Mia! movie: The soundtrack is number one on the iTunes top album chart, and Abba’s Gold: Greatest Hits, has jumped back into the Billboard catalog album charts after a two year absence, where it currently sits at number six. An Apple spokesperson commented, “Often times there are relations between songs prominently placed in movies or ads and their success on the iTunes charts.”