What movie do you most want to see but for some reason have never gotten around to watching?
There are a lot. Most of them being short films I hear about from shared Google Reader feeds that Rocky and others let me know about.
I would also probably best include here the last Studio Ghilbi movie "Gake no Ue no Ponyo", literally "Ponyo on the Cliff" or "Ponyo on the Cliff by the Sea" if one were to go for the English release title. I love Ghibli movies so much, it is strange I still haven't gotten around to seeing this even when I've had it for the longest time.