Wheee. I might check out Blades of Grass as people keep mentioning it.
Sure, definitely watch Ghost in the Shell if you liked The Matrix, or sci-fi movies, or movies that try and screw with your mind and make you think.
EDIT: Ghost in the Shell is also an anime series, so google search the movie to watch online, or download a torrent/use a media crawler/watch on sockshare or something. The sequal is subtitled 'Innocence' with a scene that took two damn years to animate by itself...
Princess Mononoke is my favorite movie of all time... Animation aside, wolves aside... it is just a profound movie. And if you would like to acknowledge the animation, it is an artistic masterpiece that (like Satoshi Kon) often manages to express concepts, feelings and use camera movements one would usually only come to expect from a live action feature.
Haven't seen The Lion King? What??? It's fun, but you may cry at times. Beautiful background art an it is animated with soul. My only problem with it is Disney won't acknowledge the fact it was meant to be a remake of a 50's anime.
Finding Nemo is the most accurate CG underwater environment I've seen so far and it is hilarious. Tip Top and I watched it baked and we were in hysterics the whole way through.