Trivia: The Japanese J-Pop duo, Puffy, is known in the U.S. as Puffy AmiYumi due to avoiding legal differences with Sean ("Puff Daddy"/"Puffy"/"P-Diddy"/"Diddy") Combs. They perform not only the theme for their Flash-animated series but also wrote and sing the theme for Teen Titans.
The real-life counterparts to the cartoon version - Ami (pronounced "AH-me") Onuki and Yumi (pronounced "YOU-me") Yoshimura - appear at the start and end of each show doing some comedy routines. In Season Two, which began April 22nd, they can also be seen holding title cards. Their official web site can be found here.