The late Muhammad Ali was not only a champion fighter and cultural figure, but also no slouch in the advertising ring.
While many have used Ali's image or voice in their ads, including Apple (Think Different commercial) and Gatorade, I'm not aware of Ali hawking much in the way of technology. One exception was this 2004 IBM Super Bowl ad during which the company pushes Linux and open source computing, something it had been behind since the late 1990s. The ad features a young boy (depicted as "Linux" in related IBM ads) soaking up vintage video of Ali boasting "I shook up the world!" and then sitting face-to-face with the boxer, who urges the kid to "shake things up" and "shake up the world."
IBM's efforts in Linux resulted in the company doing some fighting of its own, when SCO sued Big Blue for $1B, claiming that IBM intentionally hurt Unix to aid Linux (the suit was dismissed earlier this year).