This Dreamwork's animated film - almost a classic now, (watched it on DVD today - havent watched for quite a while). Spirit is really a masterful piece of 3D and 2D integration. Articles like this one from DigitalContentProducer and this one as well - cover how the pipeline and logic works. I quite like how this artform brings together the dynamic power of 3D and the artistic styling of 2D - this is something I would like to try at some point.
[images from the Running Free site]
The soundtrack (Brian Adams) is a nice mix of orchestral and pop and rounds out a splendid film in its conception, visuals, sound and more.