Muhammad Ali Memorial -- Final Tributes from Bill Clinton and Billy Crystal

Muhammad Ali's memorial service was punctuated by emotional and humorous stories about his life ... as told by his family and famous friends.

Billy Crystal was a close friend and told the packed arena in Louisville about the first time they met ... and how Ali reacted to Crystal's impression of him.

Many, many others spoke during the nearly 4-hour long ceremony. A scruffy Crystal joked, "I was clean shaven when this started."

Ali's widow, Lonnie ... 3 of his daughters ... Sen. Orrin Hatch and Bryant Gumbel also shared their memories.

President Bill Clinton delivered the final eulogy of the memorial, talking about the one thing Ali never got enough credit for -- his intelligence.