BBC learning English presents the Simpson Family in the entertainment section. You can download the programme : audio and script, and see some vocabulary. Those files are always difficult to use as is in class, but you can download and edit them with audacity, and use only the short passages you find relevant.
and here is where you can download all the episodes (but not more than 10 a week)
Here is a page of addresses to download cartoons
The Simpsons’ episode guide and facts