Katie Couric ended her nearly five-year tenure as the anchor of the "CBS Evening News" on Thursday. Couric looked back at some of her biggest moments during her historic run as the first solo woman anchor of a network newscast. The greatest hits included her iconic interviews with Sarah Palin, as well as sit-downs with a long list of presidents, celebrities and boldfaced names and reports from around the world, with events leading right up to the killing of Osama bin Laden and the royal wedding.Couric kept things simple in her sign-off.