Cartoon Brew has a great interview with John Kricfalusi regarding his Simpsons Couch Gag Intro and the process involved with creating it. If you're not familiar, John Kricfalusi is the man responsible for Ren and Stimpy (among other things) and the style certainly shows. All and all, the actual bit is incredibly weird, somewhat offputting and `gross` in that way you can't really put your finger on. However, the process of creation is an interesting one so it's certainly a worthwhile read.