have I mentioned how much I loved the Brave and the Bold cartoon? it seemed custom designed for a fan like me, one who remembers when superheroes used to smile on occasion (even Batman). not that it only did light stories- check out "Chill of the Night" for one example of a well done serious story. great voice acting there, too.
it seems the norm to do a musical episode in nearly every series these days. Buffy, Xena, Grey's Anatomy, you name it, it seems to be very common. here's a scene from the Brave and the Bold. not that this is the first time Batman has sang.