I remember hearing the end theme once on the radio and it had a woman saying the words "OH WELL" (or something like that) during it, although it's not heard on the show i think this is the title of the piece. Don't know who the artist is.
I think (but I am open to being put in my place) that it is called something like the Bottom Theme. It is played on the TV series by a group called the Bum Notes, and it is definitely based on a more well known jazzy tune.