Confessions on a Dance Floor (Warner Bros., 2005) has become one of Madonna's best selling albums, with international hits such as "Hung Up" and "Sorry". The album led to the most successful concert tour of her career, the Confessions Tour. It was co-produced by Stuart Price and contains collaborations with Mirwais Ahmadzaï, formerly of French synthpop group Taxi Girl. According to Rolling Stone, "This is an album designed for maximum volume. It's all motion, action, speed. (...) Unlike the crystalline precision of latter-day Madonna discs like Ray of Light and Music, the sonic signature here is a powerhouse density." Madonna has been regarded as "one of the greatest pop acts of all time" by various sources. In 1999, she identified musical influences that impacted her such as Karen Carpenter, The Supremes and Led Zeppelin, and dancers like Martha Graham and Rudolf Nureyev. Guinness World Records list Madonna as the world's most successful female recording artist of all time and the top-earning female singer in the world with an estimated net worth of over US$400 million, having sold over 200 million records worldwide. In 2008, her eleventh studio album, Hard Candy, was released. On March 10, 2008, she was inducted into the Rock and Roll Hall of Fame. Since the late 1990s, Madonna has been a devotee of the Kabbalah Centre and a disciple of its head, Rabbi Philip Berg, and his wife Karen. Madonna has defended her Kabbalah studies by stating it "would be less controversial if I joined the Nazi Party" and that the Kabbalah is "not hurting anybody." In 2007, Madonna also directed her first film, Filth and Wisdom.
