Billie Joe Armstrong Adds a Song to 'American Idiot'.

The Broadway musical ''American Idiot'' received a healthy shot in the arm last week as Billie Joe Armstrong, the frontman and lead guitarist for the rock band Green Day, performed in the devilish role of the heroin dealer St. Jimmy for a regular complement of eight performances. A rock opera set to more than 20 Green Day songs, ''American Idiot'' grossed $1,092,334 for the week, according to the producers - a significant improvement over the show's weekly average gross of $740,000 since opening on April 20 at the St. James Theater. The maximum possible gross for that week of performances would have been about $1.3 million. For his final performance on Sunday night, Mr. Armstrong also composed a brief number that he played - and which can be watched here or in the above video - after the curtain call and before the encore, ''Good Riddance (Time of Your Life).'' He pulled out a piece of paper, laid it by the lip of the stage, and began strumming out an ode about his musical theater debut: [ABSTRACT FROM AUTHOR]