Pop superstar Lady Gaga, U2 and Usher have been selected to perform at a special ceremony honoring the tenth anniversary of former President Bill Clinton's charitable foundation.  The concert will take place October 15th at the Hollywood Bowl, and proceeds will benefit the William J. Clinton Foundation, which has raised more than $10 billion for various charities in its ten-year history.  Organizers have also struck a deal with Yahoo to broadcast the festivities live on the Internet.