The Simpsons isn't as good as it used to be, but I still like watching it. Even bad Simpsons episodes are far better than almost everything else on TV.
My favorites of course have always been the annual Treehouse of Horror episodes. These episodes really let the writers go crazy and create some very funny and creepy stories, often times paying homage to famous horror and suspense titles.
I thought this year's episode was pretty good, especially since part of it was a zombie story. It's up on Hulu right now, check it out below while you can (Hulu videos don't stick around for long, unfortunately).
Edit: For some reason the embed works sometimes, doesn't work others. I'm starting to like Hulu less and less everyday. If the video isn't showing try this. If that doesn't work, try this (sorry media companies, but you did this to yourself).