Now I'm sure that this isn't exactly honoring Fox's copyrights, so we'll see how long it stays up... but a site called AllSimps.com has acquired Flash episodes for every single Simpsons episode ever - from Season 1 through Season 18.As Napster did, AllSimps.com claims they "don't host any videos of the Simpsons or upload them", but they do act as a conduit for those who do. If you haven't yet purchased all of the Simpsons' seasonal DVDs, or memorized every line in syndication, then this site could be a good distraction for you.
http://www.allsimps.com/