This is me channeling Joshua Porter. For me, the most interesting phenomenon in the upcoming Simpsons Movie is how their website is truly interactive. I'm really talking about one feature, the ability to create your own avatar, and it's something everyone is getting into.
I think this is a sign of good design. I mean most movie websites simply give you the typical features: trailers, wallpapers, images, etc. The avatar feature adds a new dimension and it's not something every movie can replicate (because a) Simpsons is an animated feature and b) it's part of our shared pop culture consciousness).
It's the "x-factor" that's present in a lot of social design sites such as Friendster, Multiply, Facebook, Livejournal, Blogger, Del.icio.us, Twitter, etc. You never thought it'd have that big an impact, yet it does. That's why personalized Simpsons avatars are making its way to various blogs and indirectly promoting the movie (and it's honestly one feature I imagine that will outlive the movie itself).