Robert Downey Jr. and “Iron Man” once again reigned supreme in its second week at the weekend box office, trouncing a dismal “Speed Racer” by more than $30 million. “Iron Man” took in $50.5 million after its opening weekend of $100.8 million. “Speed Racer” ($20.2 million) barely edged “What Happens in Vegas” ($20 million), with “Made of Honor” ($7.6 million) and “Baby Mama” ($5.8 million) filling out the top 5.

Madonna bumped Mariah from the No. 1 spot on the Billboard 200. Unfortunately for Madge, a German techno band called Scooter unseated her from the top of the UK charts. Leona Lewis drops to third, followed by chart newcomers Lyfe Jennings, Def Leppard, the Roots, Portishead, and Mudcrutch.

Nielsen ratings for the week of April 28 can be found here. When something other than “American Idol” or “Dancing With the Stars” occupies spots 1-4, we’ll let you know.

Ron Paul’s “The Revolution” finally hit the top spot on the NYT non-fiction list in its second week out, followed by the latest “memoir” from Augusten Burroughs. Also on the non-fiction list: Cokie Roberts, Jimmy Carter, Fareed Zakaria, and Sidney Poitier. Hard as it is to believe, James Patterson has a new book out, and it tops this week’s fiction list.