The television cartoon South Park aired an episode on July 4, 2001 called Super Best Friends. In it, the founders of the world's great religions -- including Mohammed -- team up for super-hero action. Mohammed (seen here) is depicted repeatedly throughout the show. The entire episode can be viewed online here.
(Hat tip: Dayenu and Alouette.)
Spike TV created a parody advertisement for an imaginary video game called Holy War, featuring religious icons battling to the death. One of the characters is Mohammed, who is shown first defeating Joseph Smith...
...and then getting beaten by Moses, who cuts off his head with the Ten Commandments. You can view a streaming video of the Holy War ad at this site.
(Hat tip: Andrew.)