If you guys liked that wonderful Futurama episode then Hachiko would be prefect.
It's based on a true story, and the latest version of the story is a movie from 2009 with Richard Gere. You may think it's just anohter one of those dog movies where a dog shows up and changes the people's lives but if you don't know the story of Hachiko then you're in for a surprise.
Even if you read the wikipedia entry I think it'll get you. It gets me every time.