Have you tried TMDb? http://api.themoviedb.org/2.1/

I've played with it and seems good enough.

TMDb is pretty decent (I use it to keep track of my personal movie collection [1]), but a lot of the data is missing/incomplete.

It's a whole lot better than nothing, but it's far from perfect.

[1] http://moviedb.samwarmuth.com

Freebase? It has data on most movies in IMDB. And an open API.

I really want an API that provides info on TV shows. Ever since I heard about the Tommyverse[1] I've wanted to build an application that automatically maps it and lets you play around with the connections between shows, and while it's technically possible to do it with the data IMDB does make available, you can't easily make it public and it's a real hassle.

[1] http://home.vicnet.net.au/~kwgow/crossovers.html